Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment
Balance at beginning of period at Dec. 31, 2018	$ 1,063,198		$ 119	$ 1,079,188	$ (16,109)	$ 0
Balance at beginning of period (in shares) at Dec. 31, 2018			119,078
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	109,798					109,798
Other comprehensive income (loss)	(1,897)				(1,897)
Dividends declared	(36,998)					(36,998)
Net issuances of restricted stock	0
Net issuances of restricted stock (in shares)			281
Stock-based compensation expense	11,244			11,244
Repurchases of common stock	(68,316)		$ (1)			(68,315)
Repurchases of common stock (in shares)			(1,038)
Balance at end of period at Mar. 31, 2019	1,077,029		$ 118	1,090,432	(18,006)	4,485
Balance at end of period (in shares) at Mar. 31, 2019			118,321
Balance at beginning of period at Dec. 31, 2018	1,063,198		$ 119	1,079,188	(16,109)	0
Balance at beginning of period (in shares) at Dec. 31, 2018			119,078
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	341,591
Balance at end of period at Sep. 30, 2019	1,111,830		$ 116	1,113,990	(25,871)	23,595
Balance at end of period (in shares) at Sep. 30, 2019			116,097
Balance at beginning of period at Mar. 31, 2019	1,077,029		$ 118	1,090,432	(18,006)	4,485
Balance at beginning of period (in shares) at Mar. 31, 2019			118,321
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	114,612					114,612
Other comprehensive income (loss)	2,146				2,146
Dividends declared	(36,597)					(36,597)
Net issuances of restricted stock	0		$ 1	(1)
Net issuances of restricted stock (in shares)			271
Stock-based compensation expense	11,670			11,670
Repurchases of common stock	(59,633)		$ (1)			(59,632)
Repurchases of common stock (in shares)			(1,031)
Balance at end of period at Jun. 30, 2019	1,109,227		$ 118	1,102,101	(15,860)	22,868
Balance at end of period (in shares) at Jun. 30, 2019			117,561
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	117,181					117,181
Other comprehensive income (loss)	(10,011)				(10,011)
Dividends declared	(36,235)					(36,235)
Net issuances of restricted stock	0
Net issuances of restricted stock (in shares)			(3)
Stock-based compensation expense	11,889			11,889
Repurchases of common stock	(80,221)		$ (2)			(80,219)
Repurchases of common stock (in shares)			(1,461)
Balance at end of period at Sep. 30, 2019	1,111,830		$ 116	1,113,990	(25,871)	23,595
Balance at end of period (in shares) at Sep. 30, 2019			116,097
Balance at beginning of period at Dec. 31, 2019	1,143,683	$ (558)	$ 115	1,127,487	(19,986)	36,067	$ (558)
Balance at beginning of period (in shares) at Dec. 31, 2019			115,120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	89,915					89,915
Other comprehensive income (loss)	(13,700)				(13,700)
Dividends declared	(39,441)					(39,441)
Net issuances of restricted stock	0		$ 1	(1)
Net issuances of restricted stock (in shares)			745
Stock-based compensation expense	13,525			13,525
Repurchases of common stock	(63,499)		$ (1)			(63,498)
Repurchases of common stock (in shares)			(1,263)
Balance at end of period at Mar. 31, 2020	1,129,925		$ 115	1,141,011	(33,686)	22,485
Balance at end of period (in shares) at Mar. 31, 2020			114,602
Balance at beginning of period at Dec. 31, 2019	1,143,683	$ (558)	$ 115	1,127,487	(19,986)	36,067	$ (558)
Balance at beginning of period (in shares) at Dec. 31, 2019			115,120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	211,860
Balance at end of period at Sep. 30, 2020	1,194,029		$ 114	1,167,109	(15,996)	42,802
Balance at end of period (in shares) at Sep. 30, 2020			114,180
Balance at beginning of period at Mar. 31, 2020	1,129,925		$ 115	1,141,011	(33,686)	22,485
Balance at beginning of period (in shares) at Mar. 31, 2020			114,602
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46,196					46,196
Other comprehensive income (loss)	6,534				6,534
Dividends declared	(38,975)					(38,975)
Net issuances of restricted stock	0
Net issuances of restricted stock (in shares)			33
Stock-based compensation expense	13,035			13,035
Repurchases of common stock	(9)		$ 0			(9)
Repurchases of common stock (in shares)			0
Balance at end of period at Jun. 30, 2020	1,156,706		$ 115	1,154,046	(27,152)	29,697
Balance at end of period (in shares) at Jun. 30, 2020			114,635
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	75,749					75,749
Other comprehensive income (loss)	11,156				11,156
Dividends declared	(38,969)					(38,969)
Net issuances of restricted stock	0
Net issuances of restricted stock (in shares)			(2)
Stock-based compensation expense	13,063			13,063
Repurchases of common stock	(23,676)		$ (1)			(23,675)
Repurchases of common stock (in shares)			(453)
Balance at end of period at Sep. 30, 2020	$ 1,194,029		$ 114	$ 1,167,109	$ (15,996)	$ 42,802
Balance at end of period (in shares) at Sep. 30, 2020			114,180