Common Stock and Preferred Stock - Summary of Preferred Stock Activity (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Temporary Equity [Line Items]
Beginning balance	$ 614,378	$ 551,452
Preferred stock return	29,277	52,427
Accretion of preferred stock	5,285	10,499
Conversion to common stock upon the IPO	(648,940)
Ending balance		614,378
Class A Preferred Stock [Member]
Temporary Equity [Line Items]
Beginning balance	174,199	152,689
Preferred stock return	11,219	19,505
Accretion of preferred stock	1,005	2,005
Conversion to common stock upon the IPO	(186,423)
Ending balance		174,199
Class B Preferred Stock [Member]
Temporary Equity [Line Items]
Beginning balance	285,035	250,572
Preferred stock return	18,058	32,922
Accretion of preferred stock	763	1,541
Conversion to common stock upon the IPO	(303,856)
Ending balance		285,035
Junior Preferred Stock [Member]
Temporary Equity [Line Items]
Beginning balance	155,144	148,191
Accretion of preferred stock	3,517	6,953
Conversion to common stock upon the IPO	(158,661)
Ending balance		$ 155,144