Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Additional Information (Detail)

v2.4.0.8
Share-Based Compensation - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Share-based compensation expense $ 1.3 $ 0.6
Unrecognized compensation cost related to nonvested common shares $ 11.1  
Weighted average period for recognition of cost 2 years 1 month 6 days