Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 108,509	$ 53,274	$ 245,283	$ 282,114
Cumulative effect adjustment of new accounting standards	0	0	0	(1,541)
Other Comprehensive Income (Loss):
Net unrealized gain on derivatives	0	0	0	1,379
Reclassification adjustment of derivatives and designated hedges into net income	(223)	(224)	(663)	(4,078)
Retirement liability adjustment	305	325	892	903
Total	82	101	229	(1,796)
Comprehensive Income	108,591	53,375	245,512	278,777
Comprehensive Income Attributable to Noncontrolling Interests	(1,767)	(10,293)	(5,066)	(14,020)
Comprehensive Income Adjusted for Noncontrolling Interests	$ 106,824	$ 43,082	$ 240,446	$ 264,757