Financial Instruments	12 Months Ended
Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial Instruments The Company’s indebtedness creates interest rate risk on its variable-rate debt. The Company uses derivative financial instruments to manage its exposure to interest rate risk. The Company does not hold or issue derivative financial instruments for trading or speculative purposes. The Company has interest rate cap agreements that entitle it to payments from the counterparty of the amount, if any, by which three-month LIBOR exceeds 1.5% during the agreement period. The interest rate cap agreements are in effect from January 17, 2017 through December 31, 2018 with a combined notional amount of $1.4 billion. As of December 31, 2017 and 2016, the interest rate cap agreements had a fair value of $5 million and are classified within Other Assets on the Consolidated Balance Sheets. The fair value of the Company’s interest rate cap agreements is classified as Level 2 in the fair value hierarchy. The valuation of the interest rate cap agreements is derived by using a discounted cash flow analysis on the expected cash receipts that would occur if variable interest rates rise above the strike rates of the caps. This analysis reflects the contractual terms of the interest rate cap agreements, including the period to maturity, and uses observable market-based inputs, including LIBOR curves and implied volatilities. The Company also incorporates insignificant credit valuation adjustments to appropriately reflect the respective counterparty’s nonperformance risk in the fair value measurements. The counterparty credit spreads are based on publicly available credit information obtained from a third party credit data provider. For additional details, see Note 10 (Long-Term Debt). During the first quarter of 2017, the Company designated the interest rate cap agreements as cash flow hedges. The effective portion of changes in the fair value of derivatives that qualify as cash flow hedges is recorded in Accumulated other comprehensive loss and is subsequently reclassified into Interest expense in the period when the hedged forecasted transaction affects earnings. If a derivative is deemed to be ineffective, the ineffective portion of the change in fair value of the derivative is recognized directly into earnings. The Company's interest rate cap agreements were deemed effective during 2017, and the Company expects the derivatives will continue to be effective for the next twelve months. The Company recorded an insignificant gain, net of tax expense, for the effective portion of the interest rate cap agreements into Accumulated other comprehensive loss for the year ended December 31, 2017. During 2017, the Company reclassified an insignificant amount from Accumulated other comprehensive loss into Interest expense. The Company expects to reclassify $5 million from Accumulated other comprehensive loss into Interest expense during the next twelve months. Prior to the election of hedge accounting treatment, the Company recognized less than $1 million and $3 million of Interest income during 2017 and 2016, respectively, in the Company's Consolidated Statement of Operations related to the changes in the fair value of the interest rate cap agreements.

Financial Instruments

The Company’s indebtedness creates interest rate risk on its variable-rate debt. The Company uses derivative financial instruments to manage its exposure to interest rate risk. The Company does not hold or issue derivative financial instruments for trading or speculative purposes.

The Company has interest rate cap agreements that entitle it to payments from the counterparty of the amount, if any, by which three-month LIBOR exceeds 1.5% during the agreement period. The interest rate cap agreements are in effect from January 17, 2017 through December 31, 2018 with a combined notional amount of $1.4 billion. As of December 31, 2017 and 2016, the interest rate cap agreements had a fair value of $5 million and are classified within Other Assets on the Consolidated Balance Sheets.

The fair value of the Company’s interest rate cap agreements is classified as Level 2 in the fair value hierarchy. The valuation of the interest rate cap agreements is derived by using a discounted cash flow analysis on the expected cash receipts that would occur if variable interest rates rise above the strike rates of the caps. This analysis reflects the contractual terms of the interest rate cap agreements, including the period to maturity, and uses observable market-based inputs, including LIBOR curves and implied volatilities. The Company also incorporates insignificant credit valuation adjustments to appropriately reflect the respective counterparty’s nonperformance risk in the fair value measurements. The counterparty credit spreads are based on publicly available credit information obtained from a third party credit data provider. For additional details, see Note 10 (Long-Term Debt).

During the first quarter of 2017, the Company designated the interest rate cap agreements as cash flow hedges. The effective portion of changes in the fair value of derivatives that qualify as cash flow hedges is recorded in Accumulated other comprehensive loss and is subsequently reclassified into Interest expense in the period when the hedged forecasted transaction affects earnings. If a derivative is deemed to be ineffective, the ineffective portion of the change in fair value of the derivative is recognized directly into earnings. The Company's interest rate cap agreements were deemed effective during 2017, and the Company expects the derivatives will continue to be effective for the next twelve months. The Company recorded an insignificant gain, net of tax expense, for the effective portion of the interest rate cap agreements into Accumulated other comprehensive loss for the year ended December 31, 2017. During 2017, the Company reclassified an insignificant amount from Accumulated other comprehensive loss into Interest expense. The Company expects to reclassify $5 million from Accumulated other comprehensive loss into Interest expense during the next twelve months.

Prior to the election of hedge accounting treatment, the Company recognized less than $1 million and $3 million of Interest income during 2017 and 2016, respectively, in the Company's Consolidated Statement of Operations related to the changes in the fair value of the interest rate cap agreements.