Stockholders' Equity - Roll Forward of Class A Common Shares Outstanding (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity [Abstract]
Balance at the beginning of the year	50,908,267	52,095,166
Repurchases	(1,356,861)	(1,473,863)	(4,353,801)
Stock options, rights and ESPP issuances	739,148	246,625
Restricted share issuances	241,851	242,238
Restricted share forfeitures	(165,610)	(130,119)
Shares withheld for tax obligations	(17,249)	(71,780)
Balance at the end of the period	50,349,546	50,908,267	52,095,166