Schedule of Revenue and Income for Discontinued Operations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended							12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue									$ 620,994	$ 485,574
Income (loss) before income taxes								(37,568)	230,380	194,729
Provision for income taxes								15,029	(82,118)	(74,666)
Net income (loss)								(22,539)	148,262	120,063
Net income attributable to noncontrolling interest									(114)	(178)
Net income (loss) attributable to discontinued operations	$ (193)	$ 1,543	$ (23,889)	$ 10,633	$ 38,566	$ 52,757	$ 46,306	$ (22,539)	$ 148,148	$ 119,885
Basic								$ (0.17)	$ 1.09	$ 0.85
Diluted								$ (0.16)	$ 1.07	$ 0.83
Basic								134,203	135,888	141,233
Diluted								139,929	138,702	144,014