Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 322,575	$ 345,343	$ 350,715
Cumulative effect adjustment of new accounting standards	0	(1,541)	0
Other Comprehensive (Loss) Income:
Net unrealized gain on investments, net of taxes	0	0	1,228
Realized gain on investments	0	0	(651)
Net unrealized gain on derivatives	0	1,379
Net unrealized gain on derivatives			1,063
Reclassification adjustment of derivatives and designated hedges into net income	(887)	(4,302)
Reclassification adjustment of derivatives and designated hedges into net income			(42)
Retirement liability adjustment	153	85	1,393
Total	(734)	(2,838)	2,991
Comprehensive Income	321,841	340,964	353,706
Comprehensive Income Attributable to Noncontrolling Interests	(7,140)	(17,742)	(15,441)
Comprehensive Income Adjusted for Noncontrolling Interests	$ 314,701	$ 323,222	$ 338,265