Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 79,871	$ 69,193	$ 228,840	$ 105,589
Cumulative effect adjustment of new accounting standards (see Note 2)	0	0	(1,541)	0
Other Comprehensive Income (Loss):
Net unrealized gain on investments, net of taxes	0	158	0	456
Net unrealized (loss) gain on derivatives	0	(495)	1,379	(106)
Reclassification adjustment of derivatives and designated hedges into net income	(221)	25	(3,854)	164
Retirement liability adjustment	307	369	578	746
Total	86	57	(1,897)	1,260
Comprehensive Income	79,957	69,250	225,402	106,849
Comprehensive Income Attributable to Noncontrolling Interests	(1,582)	(5,341)	(3,727)	(10,911)
Comprehensive Income Adjusted for Noncontrolling Interests	$ 78,375	$ 63,909	$ 221,675	$ 95,938