SCHEDULE I - Parent Company Information (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed statements of comprehensive income (loss)
Net income	$ 6,553	$ (2,229)	$ 9,692	$ 1,610	$ 2,211	$ (7,194)	$ 3,229	$ 3,289	$ 3,648	$ 2,316	$ 3,481	$ 5,063	$ 15,626	$ 1,535	$ 14,508
Derivative instruments
Unrealized losses on derivative instruments													(187)	(4,311)	(8,933)
Reclassification adjustment for losses included in net income													1,485	6,037	10,959
Net gain recognized in other comprehensive income													1,298	11,869	2,026
Tax benefit related to items of other comprehensive income (loss)													(435)	(4,208)	(448)
Other comprehensive income													863	7,661	1,578
Total comprehensive income													16,489	9,196	16,086
Parent Company
Condensed statements of comprehensive income (loss)
Net income													15,626	1,535	14,508
Derivative instruments
Unrealized losses on derivative instruments													(187)	(1,039)	(2,144)
Reclassification adjustment for losses included in net income													1,485	1,511	2,965
Net gain recognized in other comprehensive income													1,298	472	821
Tax benefit related to items of other comprehensive income (loss)													(435)	(16)	(30)
Other comprehensive income (loss) from parent													863	456	791
Other comprehensive income (loss) from subsidiaries														7,205	787
Other comprehensive income													863	7,661	1,578
Total comprehensive income													$ 16,489	$ 9,196	$ 16,086