Long-term Debt (Tables)

3 Months Ended

Mar. 31, 2017

Debt Disclosure [Abstract]

Summary of Long-term Debt

The following table provides a summary of the Company's Notes and the fair values based on quoted market prices in less active markets as of March 31, 2017 and December 31, 2016:

						Level 2 Fair Value as of
	Principal Amount at Par		Issuance Date	Maturity	Interest Payment Dates	March 31, 2017		December 31, 2016
	(in millions)					(in millions)
4.375% Senior Notes	$	1,000	October 2016	2026	May 15 and November 15	$	986	$	975
5.50% Senior Notes	700		February 2015	2022	April 15 and October 15	745		758
5.875% Senior Notes	800		February 2015	2025	April 15 and October 15	860		868
5.750% Senior Notes	400		February 2014	2024	March 1 and September 1	429		431
5.375% Senior Notes	500		February 2013	2021	February 1 and August 1	535		539
	$	3,400