Stockholders' Equity - Changes in Noncontrolling Interest (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Class of Stock [Line Items]
Noncontrolling Interest, Beginning of Period			$ 42,274
Net Income (Loss)	245	(838)	25	(1,045)
Common Stock and Unit Distributions			(19,286)
Conversion of Units to Common Stock			0	0
Noncontrolling Interest, End of Period	44,034		44,034
Noncontrolling Interest
Class of Stock [Line Items]
Noncontrolling Interest, Beginning of Period			42,274	45,919
Net Income (Loss)			25	(1,045)
Common Stock and Unit Distributions			(792)	0
Other Comprehensive Income			96	207
Conversion of Units to Common Stock			(804)	(2,469)
Reallocation—Additional Paid in Capital			3,206	186
Reallocation-Other Comprehensive Income			29	41
Noncontrolling Interest, End of Period	$ 44,034	$ 42,839	$ 44,034	$ 42,839