Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other comprehensive income (loss):
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ 4,245	$ 18	$ (36,556)
Partnership Interest [Member]
Net income	26,209	55,788	13,001
Other comprehensive income (loss):
Unrealized loss on derivative instruments	0	0	(61,625)
Amortization of loss on settlement of derivative instruments recognized in net income	9,466	9,467	5,575
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	4,220	11	28,363
Less: reclassification adjustment for change in fair value of derivative instruments included in net income	25	7	(3,294)
Other comprehensive income (loss)	13,711	9,485	(30,981)
Comprehensive income (loss)	39,920	65,273	(17,980)
Less: comprehensive income (loss) attributable to noncontrolling interests:
Net income attributable to noncontrolling interests	865	590	376
Other comprehensive (loss) income attributable to noncontrolling interests	(31)	9	0
Comprehensive income attributable to noncontrolling interests	834	599	376
Comprehensive income (loss) attributable to the Company	39,086	64,674	(18,356)
Parent Company [Member]
Net income	26,209	55,788	13,001
Other comprehensive income (loss):
Unrealized loss on derivative instruments	0	0	(61,625)
Amortization of loss on settlement of derivative instruments recognized in net income	9,466	9,467	5,575
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	4,220	11	28,363
Less: reclassification adjustment for change in fair value of derivative instruments included in net income	25	7	(3,294)
Other comprehensive income (loss)	13,711	9,485	(30,981)
Comprehensive income (loss)	39,920	65,273	(17,980)
Less: comprehensive income (loss) attributable to noncontrolling interests:
Net income attributable to noncontrolling interests	342	4,418	4,185
Other comprehensive (loss) income attributable to noncontrolling interests	(3)	29	(69)
Comprehensive income attributable to noncontrolling interests	339	4,447	4,116
Comprehensive income (loss) attributable to the Company	$ 39,581	$ 60,826	$ (22,096)