Results of Operations Associated with Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 150,304	$ 3,808,217		$ 3,308,921
Income from operations before income taxes	75,074	246,570		88,579
Gain on sale before income taxes	0	12,684		0
Total income from discontinued operations before taxes	75,074	259,254		88,579
Provision for income taxes	68,244	116,023		39,578
Income from discontinued operations	$ 6,830	$ 143,231	[1]	$ 49,001	[1]

[1] Reclassified to conform to current presentation.