STATEMENT OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Shares issued, beginning balance at Dec. 31, 2018		52,598,005
Equity, beginning balance at Dec. 31, 2018	$ 2,042,656	$ 526	$ 1,727,492	$ 320,869	$ (2,145)	$ (4,086)
Net income	93,660	0		93,660	0	0
Other comprehensive income	160	0		0		160
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	0	$ 0	0	(1,218)	0	1,218
Common stock issued, shares		88,629
Common stock issued, value	(5,353)	$ 1	(7,499)	0	2,145	0
Common stock dividends - $0.50 and $0.46 per share per quarter as of 2019 and 2018, respectively	(26,343)	$ 0	227	(26,570)	0	0
Shares issued, ending balance at Mar. 31, 2019		52,686,634
Equity, ending balance at Mar. 31, 2019	$ 2,104,780	$ 527	1,720,220	389,177	0	(5,144)
Document Period End Date	Mar. 31, 2020
Shares issued, beginning balance at Dec. 31, 2019	52,771,749	52,771,749
Equity, beginning balance at Dec. 31, 2019	$ 2,129,390	$ 528	1,733,092	402,509	0	(6,739)
Net income	91,677	0	0	91,677	0	0
Other comprehensive income	224	$ 0	0	0	0	224
Common stock issued, shares		89,059
Common stock issued, value	(3,736)	$ 1	(3,737)	0	0	0
Common stock dividends - $0.50 and $0.46 per share per quarter as of 2019 and 2018, respectively	$ (28,543)	$ 0	232	(28,775)	0	0
Shares issued, ending balance at Mar. 31, 2020	52,860,808	52,860,808
Equity, ending balance at Mar. 31, 2020	$ 2,189,012	$ 529	$ 1,729,587	$ 465,411	$ 0	$ (6,515)