Short And Long-Term Debt Schedule of Debt (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019		Feb. 21, 2020	Mar. 31, 2019	Dec. 31, 2018	Feb. 28, 2018	Jan. 31, 2017
Principal Amount
Long-term Debt, Gross		$ 3,472,000,000
Unamortized Discount and Debt Issuance Costs
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		27,000,000
Net Amount
Outstanding borrowings, long-term debt		$ 3,445,000,000
LIBOR
Net Amount
Description of variable interest rate basis		LIBOR
ABR
Net Amount
Description of variable interest rate basis		ABR
Revolving Credit Facility | Line of Credit
Principal Amount
Outstanding borrowings, short-term debt, line of credit facility		$ 190,000,000	[1],[2]			$ 270,000,000
Net Amount
Outstanding borrowings, short-term debt, line of credit facility		190,000,000	[1],[2]			270,000,000
Line of credit facility borrowing capacity		1,425,000,000					$ 1,400,000,000	$ 1,050,000,000
Long-term Line of Credit		$ 190,000,000	[1],[2]			270,000,000
Revolving Credit Facility | Line of Credit | LIBOR | Less than or equal to 3.50 to 1.00 but greater than or equal to 2.50 to 1.00
Net Amount
Debt Instrument, basis spread on variable rate		2.25%
Revolving Credit Facility | Line of Credit | ABR | Less than or equal to 3.50 to 1.00 but greater than or equal to 2.50 to 1.00
Net Amount
Debt Instrument, basis spread on variable rate		1.25%
Revolving Credit Facility | Line of Credit | Subsequent Event
Principal Amount
Outstanding borrowings, short-term debt, line of credit facility				$ 310,000,000
Net Amount
Outstanding borrowings, short-term debt, line of credit facility				310,000,000
Long-term Line of Credit				310,000,000
Revolving Credit Facility | Letter of Credit
Principal Amount
Outstanding borrowings, short-term debt, line of credit facility		$ 57,000,000
Net Amount
Outstanding borrowings, short-term debt, line of credit facility		57,000,000
Long-term Line of Credit		$ 57,000,000
Revolving Credit Facility | Letter of Credit | Subsequent Event
Principal Amount
Outstanding borrowings, short-term debt, line of credit facility				57,000,000
Net Amount
Outstanding borrowings, short-term debt, line of credit facility				57,000,000
Long-term Line of Credit				$ 57,000,000
Term Loan B | LIBOR
Net Amount
Debt Instrument, basis spread on variable rate		2.25%
Debt Instrument, basis spread on variable rate, floor		0.75%
Term Loan B | ABR
Net Amount
Debt Instrument, basis spread on variable rate		1.25%
Debt Instrument, basis spread on variable rate, floor		1.75%
Term Loan B | Secured Debt
Principal Amount
Long-term Debt, Gross		$ 1,058,000,000	[2]			1,069,000,000	1,080,000,000
Unamortized Discount and Debt Issuance Costs
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	[2]	13,000,000
Net Amount
Outstanding borrowings, long-term debt		$ 1,045,000,000	[2]			1,053,000,000
Annual percentage of original principal amount for quarterly amortization payments		1.00%
Term Loan A | Secured Debt
Principal Amount
Long-term Debt, Gross		$ 717,000,000				736,000,000	$ 750,000,000
Unamortized Discount and Debt Issuance Costs
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		3,000,000
Net Amount
Outstanding borrowings, long-term debt		$ 714,000,000				732,000,000
Term Loan A | Secured Debt | LIBOR | Less than or equal to 3.50 to 1.00 but greater than or equal to 2.50 to 1.00
Net Amount
Debt Instrument, basis spread on variable rate		2.25%
Term Loan A | Secured Debt | ABR | Less than or equal to 3.50 to 1.00 but greater than or equal to 2.50 to 1.00
Net Amount
Debt Instrument, basis spread on variable rate		1.25%
Term Loan A | Secured Debt | 2018
Net Amount
Annual percentage of original principal amount for quarterly amortization payments		2.50%
Term Loan A | Secured Debt | 2019
Net Amount
Annual percentage of original principal amount for quarterly amortization payments		2.50%
Term Loan A | Secured Debt | 2020
Net Amount
Annual percentage of original principal amount for quarterly amortization payments		5.00%
Term Loan A | Secured Debt | 2021
Net Amount
Annual percentage of original principal amount for quarterly amortization payments		7.50%
Term Loan A | Secured Debt | 2022
Net Amount
Annual percentage of original principal amount for quarterly amortization payments		10.00%
5.25% Senior Notes | Senior Notes
Principal Amount
Long-term Debt, Gross		$ 550,000,000				550,000,000
Unamortized Discount and Debt Issuance Costs
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		2,000,000
Net Amount
Outstanding borrowings, long-term debt		$ 548,000,000				547,000,000
Interest Rate		5.25%
4.875% Senior Notes | Senior Notes
Principal Amount
Long-term Debt, Gross		$ 407,000,000				500,000,000
Unamortized Discount and Debt Issuance Costs
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		2,000,000
Net Amount
Outstanding borrowings, long-term debt		$ 405,000,000				497,000,000
Interest Rate		4.875%
9.375% Senior Notes | Senior Notes
Principal Amount
Long-term Debt, Gross		$ 550,000,000			$ 550	0
Unamortized Discount and Debt Issuance Costs
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		7,000,000
Net Amount
Outstanding borrowings, long-term debt		$ 543,000,000				$ 0
Interest Rate		9.375%

[1] Interest rates with respect to revolving loans under the Senior Secured Credit Facility at December 31, 2019 were based on, at the Company's option, (a) adjusted London Interbank Offering Rate ("LIBOR") plus an additional margin or (b) JP Morgan Chase Bank, N.A.'s prime rate ("ABR") plus an additional margin, in each case subject to adjustment based on the then current senior secured leverage ratio. Based on the previous quarter's senior secured leverage ratio, the LIBOR margin was 2.25% and the ABR margin was 1.25% for the three months ended December 31, 2019.

[2] The Term Loan B provides for quarterly amortization payments totaling 1% per annum of the original principal amount. The interest rate with respect to term loans under the Term Loan B is based on, at the Company’s option, (a) adjusted LIBOR plus 2.25% (with a LIBOR floor of 0.75%) or (b) ABR plus 1.25% (with an ABR floor of 1.75%).