Discontinued Operations and Divestitures - Gains on the Disposals of Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Discontinued Operations And Disposal Groups [Abstract]
Gain on disposal of discontinued operations, before income tax	$ 107,506	$ 52	$ 107,543	$ 115
Income tax expense	51,191	20	49,300	43
Gain on disposal of discontinued operations, net of tax	$ 56,315	$ 32	$ 58,243	$ 72