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																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations																	$ 304,592	$ 156,966	$ 162,330
(Loss) income from discontinued operations, net of taxes			(663)	[1]	(2,739)	[1]	(355)	[1]	150	[1]	99	[1]	(150)	[1]	(304)	[1]	(3,757)	(205)	180
Net income	47,471	[1]	51,843	[1]	20,429	[1]	181,092	[1]	45,408		42,339		37,334		31,680		300,835	156,761	162,510
Weighted average shares and assumed conversions																	111,250	100,623	105,535
Income from continuing operations																	$ 2.77	$ 1.58	$ 1.55
(Loss) income from discontinued operations, net of taxes																	$ (0.03)
Net income	$ 0.41	[2]	$ 0.45	[2]	$ 0.19	[2]	$ 1.81	[2]	$ 0.46		$ 0.42		$ 0.37		$ 0.32		$ 2.74	$ 1.58	$ 1.55
Income from continuing operations																	$ 2.73	$ 1.56	$ 1.54
(Loss) income from discontinued operations, net of taxes																	$ (0.03)
Net income	$ 0.41	[2]	$ 0.44	[2]	$ 0.19	[2]	$ 1.78	[2]	$ 0.45		$ 0.42		$ 0.37		$ 0.32		$ 2.70	$ 1.56	$ 1.54
Basic Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations																	304,592	156,966	162,330
(Loss) income from discontinued operations, net of taxes																	(3,757)	(205)	180
Net income																	300,835	156,761	162,510
Weighted average common shares outstanding, basic																	109,617	99,545	104,736
Diluted Earnings Per Share
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations																	304,592	156,966	162,330
(Loss) income from discontinued operations, net of taxes																	(3,757)	(205)	180
Net income																	$ 300,835	$ 156,761	$ 162,510
Weighted average common shares outstanding, diluted																	109,617	99,545	104,736
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities																	1,279	864	603
Restricted stock based compensation
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities																	354	214	196

[1] The amounts presented for the first two quarters of 2013 and the four quarters of 2012 are not equal to the same amounts previously reported in the respective reports on Form 10-Q and Form 10-K for each period as a result of discontinued operations. Below is a reconciliation to the previously reported amounts in Form 10-Q.

[2] The earnings per share amounts in the first quarter of 2013 were favorably impacted by the net tax benefit resulting from the revaluation of certain deferred tax assets and liabilities associated with the REIT conversion effective January 1, 2013. Additionally, the earnings per share amounts in the second quarter of 2013 were negatively impacted by $36.3 million of expenses associated with debt refinancing transactions.