Schedule 1 - Condensed Parent Company Financial Statements (Condensed Statements of Comprehensive Income) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Operating income	$ 85,301	$ 106,470	$ 80,949	$ 67,439	$ 62,794	$ 104,293	$ 86,754	$ 69,337	$ 340,159	$ 323,178	$ 333,920
Interest expense									125,383	99,054	88,543
Interest income									(25,406)	(152)	(202)
Change in fair value of interest rate swap agreements									23,742	59,779
Other (income) expense									(5,691)	(1,996)	(4,953)
Income before income taxes									211,526	178,319	256,652
Provision for income taxes (benefit)									(13,017)	(13,669)	16,914
Net income	$ 64,227	$ 88,489	$ 54,903	$ 16,924	$ (3,657)	$ 78,216	$ 66,590	$ 50,839	224,543	191,988	239,738
Comprehensive income									$ 224,543	$ 191,988	$ 239,929
Basic	$ 0.28	$ 0.38	$ 0.25	$ 0.09	$ (0.02)	$ 0.44	$ 0.37	$ 0.29	$ 1.04	$ 1.08	$ 1.35
Diluted	$ 0.28	$ 0.38	$ 0.25	$ 0.09	$ (0.02)	$ 0.44	$ 0.37	$ 0.29	$ 1.04	$ 1.08	$ 1.35
Basic									215,550	177,904	177,612
Diluted									215,931	178,399	178,175
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Other income									$ 1,596	$ 894	$ 1,629
Operating expense and other expenses									23,760	19,728	53
Operating income									(22,164)	(18,834)	1,576
Interest expense									45,759	9,426	5,211
Interest income									(25,327)	(5)
Change in fair value of interest rate swap agreements									23,741	59,779
Other (income) expense									294	(93)	1
Income before income taxes									(66,043)	(88,127)	(3,634)
Equity in earnings of subsidiaries									276,556	261,700	244,327
Income before income taxes									210,513	173,573	240,693
Provision for income taxes (benefit)									(14,030)	(18,415)	955
Net income									224,543	191,988	239,738
Comprehensive income									$ 224,543	$ 191,988	$ 239,929
Basic									$ 1.04	$ 1.08	$ 1.35
Diluted									$ 1.04	$ 1.08	$ 1.35
Basic									215,550	177,904	177,612
Diluted									215,931	178,399	178,175