Basis Of Presentation Financial Instruments - Fair Value Indebtedness Table (Details) - USD ($) $ in Millions		Mar. 31, 2020		Dec. 31, 2019	Feb. 28, 2018
Long-term debt principal amount		$ 4,030
Secured Debt | Term Loan B
Long-term debt principal amount		1,056	[1]	$ 1,058	$ 1,080
Long-term debt fair value	[2]	903		1,048
Secured Debt | Term Loan A
Long-term debt principal amount		712	[3]	717	$ 750
Long-term debt fair value	[2]	641		705
Senior Notes | 5.25% Senior Notes
Long-term debt principal amount		550		550
Long-term debt fair value	[2]	519		557
Senior Notes | 4.875% Senior Notes
Long-term debt principal amount		407		407
Long-term debt fair value	[2]	342		401
Senior Notes | 9.375% Senior Notes
Long-term debt principal amount		550		550
Long-term debt fair value	[2]	459		572
Line of Credit | Revolving Credit Facility
Line of credit facility outstanding		755	[4],[5]	190
Line of credit facility fair value	[2]	$ 755		$ 190

[1] 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%).

[2] The fair value of the Company's indebtedness is categorized as Level II.

[3] The Term Loan A provides for quarterly amortization payments, which commenced on June 30, 2018, totaling per annum 2.5%, 2.5%, 5.0%, 7.5% and 10.0% of the original principal amount of the Term Loan A, with the balance of the Term Loan A due at maturity on February 8, 2023. The interest rates with respect to the Term Loan A are based on, at the Company's option, (a) adjusted LIBOR plus an additional margin or (b) 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 March 31, 2020.

[4] In response to the rapidly evolving COVID-19 pandemic, the Company borrowed an additional $400 million under the Revolving Credit Facility in March 2020 as a proactive measure intended to increase liquidity to support our operations and supplement available cash on hand. As of March 31, 2020, the $1,425 million Revolving Credit Facility had outstanding borrowings of $755 million, as well as $56 million of outstanding letters of credit. The Revolving Credit Facility expires in February 2023 but is classified on the balance sheet as current due to the revolving nature and terms and conditions of the facility. On May 5, 2020, the Company had $815 million in outstanding borrowings under the Revolving Credit Facility and $57 million of outstanding letters of credit.

[5] Interest rates with respect to revolving loans under the Senior Secured Credit Facility at March 31, 2020 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 March 31, 2020.