Scheduled Principal Payments on Notes Payable (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Jan. 19, 2011
Debt Instrument [Line Items]
2013	$ 3,704
2014	233,993
2015	235,980
2016	113,974
2017	190,139
Thereafter	279,890
Notes payable, total	$ 1,057,680	[1]	$ 927,993	[1]	$ 342,000

[1] Excludes unamortized fair market value adjustment of $13.0 million and $15.9 million as of December 31, 2012 and 2011, respectively.