EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Numerator for basic and diluted earnings per share:
Income from continuing operations									$ 127,252	$ 127,721	$ 35,247
Income from discontinued operations					0	0	2,412	382	0	2,794	1,439
Net income	$ 38,233	$ 37,133	$ 29,156	$ 22,730	$ 23,329	$ 38,827	$ 57,929	$ 10,430	$ 127,252	$ 130,515	$ 36,686
Denominator:
Basic shares outstanding (in shares)									52,961	52,622	49,633
Dilutive effect of equity-based compensation awards (in shares)									363	310	233
Dilutive shares outstanding (in shares)									53,324	52,932	49,866
Basic earnings per share:
Income from continuing operations (in dollars per share)									$ 2.40	$ 2.43	$ 0.71
Income from discontinued operations, net of tax (in dollars per share)									$ 0.00	$ 0.05	$ 0.03
Net income (in dollars per share)	$ 0.72	$ 0.70	$ 0.55	$ 0.43	$ 0.44	$ 0.74	$ 1.1	$ 0.2	$ 2.40	$ 2.48	$ 0.74
Diluted earnings per share:
Income from continuing operations (in dollars per share)									$ 2.39	$ 2.42	$ 0.71
Income from discontinued operations, net of tax (in dollars per share)									$ 0.00	$ 0.05	$ 0.03
Net income (in dollars per share)	$ 0.72	$ 0.70	$ 0.55	$ 0.43	$ 0.44	$ 0.73	$ 1.1	$ 0.2	$ 2.39	$ 2.47	$ 0.74