Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common stock	Other paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury stock
Cumulative effect of adoption of ASU 2014-09 | Accounting Standards Update 2014-09	$ (970)			$ (970)
Balance (in shares) at Dec. 31, 2017		195,843,297
Treasury stock (in shares) at Dec. 31, 2017						(538,921)
Balance at Dec. 31, 2017	2,429,043	$ 195,843	$ 1,233,412	1,040,748	$ (37,334)	$ (3,626)
Balance (Accounting Standards Update 2014-09) at Dec. 31, 2017	2,428,073			1,039,778
Net income	42,437			42,437
Other comprehensive income	433				433
Reclassification of certain prior period tax effects from accumulated other comprehensive loss | Adjustments for new accounting pronouncement	0			7,959	(7,959)
Dividends declared on common stock	(38,705)			(38,705)
Stock-based compensation	1,223		1,223
Repurchase of common stock						(182,424)
Repurchase of common stock	(5,020)					$ (5,020)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(7,350)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)						182,424
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 5,020
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	$ (2,330)
Balance (in shares) at Mar. 31, 2018	195,843,297	195,843,297
Treasury stock (in shares) at Mar. 31, 2018						(538,921)
Balance at Mar. 31, 2018	$ 2,426,111	$ 195,843	1,227,285	1,051,469	(44,860)	$ (3,626)
Balance (in shares) at Dec. 31, 2018	196,564,907	196,564,907
Treasury stock (in shares) at Dec. 31, 2018						(538,921)
Balance at Dec. 31, 2018	$ 2,566,775	$ 196,565	1,248,576	1,163,602	(38,342)	$ (3,626)
Net income	40,926			40,926
Other comprehensive income	774				774
Dividends declared on common stock	(40,019)			(40,019)
Stock-based compensation	1,617		1,617
Share Based Compensation, Shares, Shares Issued Net Of Tax Withholdings		246,214
Share Based Compensation Value Issued Shares Net Of Tax Withholdings		$ 246
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(3,261)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(3,015)
Issuance of common stock (shares)		1,505,687
Issuance of common stock	$ 38,634	$ 1,506	37,128
Balance (in shares) at Mar. 31, 2019	198,316,808	198,316,808
Treasury stock (in shares) at Mar. 31, 2019						(538,921)
Balance at Mar. 31, 2019	$ 2,605,692	$ 198,317	$ 1,284,060	$ 1,164,509	$ (37,568)	$ (3,626)