Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Basic Net Income Per Share
Net income	$ 77,944	$ 51,705	$ 22,640	$ 69,781	$ 62,964	$ 56,276	$ 152,289	$ 189,021
Weighted average common shares outstanding (in shares)	164,773			170,746			165,748	172,807
Effect of dilutive securities:
Restricted stock (in shares)	611			761			586	672
Stock options (in shares)	35			44			36	48
Basic Net Income Per Share (in dollars per share)	$ 0.47			$ 0.41			$ 0.92	$ 1.10
Earnings Per Share, Diluted [Abstract]
Net income	$ 77,944	$ 51,705	$ 22,640	$ 69,781	$ 62,964	$ 56,276	$ 152,289	$ 189,021
Weighted average common shares outstanding (in shares)	164,773			170,746			165,748	172,807
Weighted average shares outstanding (in shares)	165,419			171,551			166,370	173,527
Diluted Net Income Per Share (in dollars per share)	$ 0.47			$ 0.41			$ 0.92	$ 1.09