Consolidated Statements Of Changes In Stockholder's Equity - USD ($)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss), Net Of Taxes [Member]	Retained Earnings [Member]
Change to beginning balance due to adoption of Accounting Standards Update 2016-03					$ 0
Beginning balance, at Dec. 31, 2018			$ 1,100,315,000	$ (126,254,000)	4,062,696,000
Beginning balance, shares at Dec. 31, 2018		1,000
Share-based compensation plans			87,000
Net increase (decrease) during the period	$ 98,148,000			98,148,000
Net income (loss)	251,608,000				251,608,000
Ending balance, shares at Mar. 31, 2019		1,000
Ending balance, at Mar. 31, 2019	5,386,602,000		1,100,402,000	(28,106,000)	4,314,306,000
Change to beginning balance due to adoption of Accounting Standards Update 2016-03					907,000
Beginning balance, at Dec. 31, 2019	$ 5,857,425,000		1,100,678,000	64,324,000	4,692,423,000
Beginning balance, shares at Dec. 31, 2019	1,000	1,000
Share-based compensation plans			103,000
Net increase (decrease) during the period	$ (178,351,000)			(178,351,000)
Net income (loss)	$ 316,645,000				316,645,000
Ending balance, shares at Mar. 31, 2020	1,000	1,000
Ending balance, at Mar. 31, 2020	$ 5,996,729,000		$ 1,100,781,000	$ (114,027,000)	$ 5,009,975,000