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		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 57,546	$ 52,506	$ 165,016	$ 257,121
Loss from discontinued operations, net of taxes		(663)		(3,757)
Net income	57,546	51,843	165,016	253,364
Weighted average shares and assumed conversions	117,389	116,872	117,183	109,300
Income from continuing operations	$ 0.50	$ 0.46	$ 1.42	$ 2.38
Loss from discontinued operations, net of taxes		$ (0.01)		$ (0.03)
Net income	$ 0.50	$ 0.45	$ 1.42	$ 2.35
Income from continuing operations	$ 0.49	$ 0.45	$ 1.41	$ 2.35
Loss from discontinued operations, net of taxes		$ (0.01)		$ (0.03)
Net income	$ 0.49	$ 0.44	$ 1.41	$ 2.32
Basic Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	57,546	52,506	165,016	257,121
Loss from discontinued operations, net of taxes		(663)		(3,757)
Net income	57,546	51,843	165,016	253,364
Weighted average common shares outstanding, basic	116,185	115,282	116,025	107,640
Diluted Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	57,546	52,506	165,016	257,121
Loss from discontinued operations, net of taxes		(663)		(3,757)
Net income	$ 57,546	$ 51,843	$ 165,016	$ 253,364
Weighted average common shares outstanding, diluted	116,185	115,282	116,025	107,640
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	886	1,165	895	1,335
Restricted stock based compensation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	318	425	263	325