Stockholders' Equity - Changes in Noncontrolling Interest (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Class of Stock [Line Items]
Noncontrolling Interest, Beginning of Period	$ 42,274
Net Loss	(220)	(207)
Distributions	(9,536)
Conversion of Units to Common Stock	0	0
Noncontrolling Interest, End of Period	43,978
Noncontrolling Interest
Class of Stock [Line Items]
Noncontrolling Interest, Beginning of Period	42,274	45,919
Net Loss	(220)	(207)
Distributions	(400)	0
Other Comprehensive Income	34	33
Conversion of Units to Common Stock	0	(99)
Reallocation-Additional Paid in Capital	2,268	116
Reallocation-Other Comprehensive Income	22	15
Noncontrolling Interest, End of Period	$ 43,978	$ 45,777