Fee and Other Income (Details) - Entity [Domain] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fee And Other Income [Line Items]
BMS cleaning fees	$ 21,741	$ 22,195	$ 44,374	$ 41,151
Management and leasing fees	4,274	5,765	8,466	11,593
Lease termination fees	2,893	4,545	6,640	8,122
Other income	10,322	8,306	19,357	15,885
Fee and other income	39,230	40,811	78,837	76,751
Interstate Properties [Member]
Fee And Other Income [Line Items]
Management and leasing fees	$ 132	$ 131	$ 271	$ 265