CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 163,622	$ 47,664	$ 26,318
Other comprehensive income (loss):
Unrealized gain (loss) on interest rate swap agreements	(1,296)
Other comprehensive income (loss)	(1,296)
Comprehensive income	162,326	47,664	26,318
Net income attributable to noncontrolling interest	(28,320)	(9,808)	(6,237)
Other comprehensive (income) loss attributable to noncontrolling interest	227
Comprehensive income attributable to common stockholders	$ 134,233	$ 37,856	$ 20,081