Quarterly report pursuant to Section 13 or 15(d)

Condensed Consolidated Balance Sheets (Parenthetical)

v2.4.1.9
Condensed Consolidated Balance Sheets (Parenthetical) (USD $)
In Thousands, except Share data, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Trade accounts receivable, allowances $ 23,763us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent $ 21,007us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
Preferred Stock, par value $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare $ 0.001us-gaap_PreferredStockParOrStatedValuePerShare
Preferred Stock, shares authorized 10,000,000us-gaap_PreferredStockSharesAuthorized 10,000,000us-gaap_PreferredStockSharesAuthorized
Preferred Stock, shares issued 0us-gaap_PreferredStockSharesIssued 0us-gaap_PreferredStockSharesIssued
Preferred Stock, shares outstanding 0us-gaap_PreferredStockSharesOutstanding 0us-gaap_PreferredStockSharesOutstanding
Class A Common Stock [Member]    
Common Stock, par value $ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
$ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Common Stock, shares authorized 100,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
100,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Common Stock, shares issued 40,673,000us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
40,287,000us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Common Stock, shares outstanding 40,673,000us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
40,287,000us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Class B Common Stock [Member]    
Common Stock, par value $ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
$ 0.001us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
Common Stock, shares authorized 60,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
60,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
Common Stock, shares issued 10,214,000us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
10,470,000us-gaap_CommonStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
Common Stock, shares outstanding 10,214,000us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
10,470,000us-gaap_CommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember