Commitments and Contingencies - Minimum Aggregate Lease Payments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Gross Rents, 2013	$ 22,151
Gross Rents, 2014	21,252
Gross Rents, 2015	20,957
Gross Rents, 2016	20,615
Gross Rents, 2017	20,115
Gross Rents, Thereafter	277,363
Gross Rents, Total lease commitments	382,453
Sublease Rents, 2013	1,850
Sublease Rents, 2014	1,725
Sublease Rents, 2015	1,657
Sublease Rents, 2016	1,530
Sublease Rents, 2017	1,519
Sublease Rents, Thereafter	4,506
Sublease Rents, Total lease commitments	12,787
Net Rents, 2013	20,301
Net Rents, 2014	19,527
Net Rents, 2015	19,300
Net Rents, 2016	19,085
Net Rents, 2017	18,596
Net Rents, Thereafter	272,857
Net Rents, Total lease commitments	$ 369,666