Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 55,732	$ 23,168	$ 107,470	$ 204,615
Loss from discontinued operations, net of taxes		(2,739)		(3,094)
Net income	55,732	20,429	107,470	201,521
Weighted average shares and assumed conversions	117,196	108,991	117,079	105,433
Income from continuing operations	$ 0.48	$ 0.22	$ 0.93	$ 1.97
Loss from discontinued operations, net of taxes		$ (0.03)		$ (0.03)
Net income	$ 0.48	$ 0.19	$ 0.93	$ 1.94
Income from continuing operations	$ 0.48	$ 0.21	$ 0.92	$ 1.94
Loss from discontinued operations, net of taxes		$ (0.02)		$ (0.03)
Net income	$ 0.48	$ 0.19	$ 0.92	$ 1.91
Basic Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	55,732	23,168	107,470	204,615
Loss from discontinued operations, net of taxes		(2,739)		(3,094)
Net income	55,732	20,429	107,470	201,521
Weighted average common shares outstanding, basic	116,114	107,400	115,944	103,755
Diluted Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	55,732	23,168	107,470	204,615
Loss from discontinued operations, net of taxes		(2,739)		(3,094)
Net income	$ 55,732	$ 20,429	$ 107,470	$ 201,521
Weighted average common shares outstanding, diluted	116,114	107,400	115,944	103,755
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	835	1,284	899	1,420
Restricted stock based compensation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	247	307	236	258