CONDENSED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY - 6 months ended Jun. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Treasury Stock	Additional Paid in Capital	Retained Earnings
Balance at beginning of period at Dec. 31, 2017	$ 413,023	$ 534	$ 0	$ 0	$ 329,993	$ 82,496
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	270,006					270,006
Dividends paid ($6.63 per share)	(355,350)				(91,122)	(264,228)
Stock compensation	4,679				4,679
Treasury stock purchase	(12,100)			(12,100)
Other	(5,388)				(5,388)
Balance at end of period at Jun. 30, 2018	$ 314,870	$ 534	$ 0	$ (12,100)	$ 238,162	$ 88,274