Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]

0001065280 (http://www.sec.gov/CIK)

Debt Disclosure [Abstract]	Period [Axis]
	2016-01-01 - 2016-12-31
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table provides a summary of the Company's outstanding long-term debt and the fair values based on quoted market prices in less active markets as of December 31, 2016 and December 31, 2015:                   Level 2 Fair Value as of   Principal Amount at Par   Issuance Date   Maturity   Interest Due Dates   December 31, 2016   December 31, 2015   (in millions)               (in millions) 4.375% Senior Notes 1,000   October 2016   2026   May 15 and November 15   $ 975   $ — 5.50% Senior Notes 700   February 2015   2022   April 15 and October 15   758   718 5.875% Senior Notes 800   February 2015   2025   April 15 and October 15   868   820 5.750% Senior Notes 400   February 2014   2024   March 1 and September 1   431   411 5.375% Senior Notes 500   February 2013   2021   February 1 and August 1   539   525