Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]
Balance at Dec. 31, 2011	$ 829,247	$ 471	$ 244,211	$ (82,177)	$ (85)	$ 666,827
Balance (Share) at Dec. 31, 2011		47,194
Issuance of common units by the Partnership to non-controlling	158,000					158,014
Stock-based compensation	5,113	0	2,397	0	0	2,716
Common dividends	(11,221)	0	0	(11,221)	0	0
Net income (loss)	568	0	0	(2,496)	0	3,064
Conversion of restricted stock, net of shares withheld for taxes	(627)	2	(629)	0	0	0
Conversion of restricted stock, net of shares withheld for taxes (Shares)		185
Hedging gains or losses reclassified to earnings	384	0	0	0	71	313
Adjustment in fair value of derivatives	1,582	0	0	0	298	1,284
Non-controlling partner's impact of conversion of restricted units and options exercise	(884)	0	0	0	0	(884)
Distribution to non-controlling interest	(32,584)	0	0	0	0	(32,584)
Changes in equity due to issuance of units by the Partnership	5,136		17,441			(12,305)
Balance at Jun. 30, 2012	$ 954,728	$ 473	$ 263,420	$ (95,894)	$ 284	$ 786,445
Balance (Share) at Jun. 30, 2012		47,379