Borrowings and Credit Arrangements (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of debt maturities

			As of December 31,						Semi-annual Coupon Rate
in millions, except interest rates	Issuance Date	Maturity Date	2017			2016
January 2017 Notes	November 2004	January 2017	$	—		$	250		5.125	%
August 2018 Term Loan	August 2013	August 2018	—			150
October 2018 Notes	August 2013	October 2018	*			600			2.650	%
January 2020 Notes	December 2009	January 2020	850			850			6.000	%
May 2020 Notes	May 2015	May 2020	600			600			2.850	%
August 2020 Term Loan	August 2015	August 2020	—			600
May 2022 Notes	May 2015	May 2022	500			500			3.375	%
October 2023 Notes	August 2013	October 2023	450			450			4.125	%
May 2025 Notes	May 2015	May 2025	750			750			3.850	%
November 2035 Notes	November 2005	November 2035	350			350			7.000	%
January 2040 Notes	December 2009	January 2040	300			300			7.375	%
Unamortized Debt Issuance Discount		2018 - 2040	(6		)	(8		)
Unamortized Deferred Financing Costs		2018 - 2040	(18		)	(24		)
Unamortized Gain on Fair Value Hedges		2020-2025	38			51
Capital Lease Obligation		Various	1			1
Long-term debt			$	3,815		$	5,420

*As of December 31, 2017, the $600 million under the October 2018 Notes is outstanding and classified as short-term debt.

Note: The table above does not include unamortized amounts related to interest rate contracts designated as cash flow hedges.

Summary of term loan and revolving credit facility agreement compliance with debt covenants

	Covenant Requirement as of December 31, 2017	Actual as of December 31, 2017
Maximum leverage ratio (1)	3.5 times	2.2 times

(1) Ratio of total debt to consolidated EBITDA, as defined by the credit agreement, for the preceding four consecutive fiscal quarters.