Other Assets - Components of Other Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Intangible assets:
Total intangible assets, net	$ 129,280	$ 47,570
Other assets:
Prepaid expenses	12,469	10,375
Deposits	10,580	6,788
Other assets	29,821	2,893
Total other assets	182,150	67,626
Lease origination costs and fair market value of leases, Acquired-in-Place [Member]
Intangible assets:
Total intangible assets, net	67,105	24,798
Tenant relations, net [Member]
Intangible assets:
Total intangible assets, net	$ 62,175	$ 22,772