Stockholders' Equity - Common Stock Outstanding, Including Unvested Restricted Shares of Common Stock (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Class of Stock [Line Items]
Common Stock, Shares, Outstanding, Beginning Balance	98,767,913
Issuance of Restricted Stock Shares	1,003,421
Common Stock, Shares, Outstanding, Ending Balance	109,980,850
Common Class A [Member]
Class of Stock [Line Items]
Common Stock, Shares, Outstanding, Beginning Balance	98,767,913	86,807,402	68,841,296
Issuance of Common Stock, Including Vesting of Restricted Stock Units	10,853,693	11,085,905	17,646,586
Issuance of Restricted Stock Shares	284,461	565,137	292,339
Repurchase and Retirement of Restricted Stock Shares	(30,245)	(225,557)	(98,603)
Conversion of Operating Partnership Units	105,028	535,026	125,784
Common Stock, Shares, Outstanding, Ending Balance	109,980,850	98,767,913	86,807,402