CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2012	$ 11,317	$ 0	$ 0	$ 9,450	$ 1,893	$ (26)
Balance (in shares) at Dec. 31, 2012		1,112	0
Components of comprehensive income:
Net income	1,010				1,010
Other comprehensive income (loss)	94					94
Issuance of common stock pursuant to employee stock options	158			158
Issuance of common stock pursuant to employee stock options (in shares)		16
Issuance of common stock pursuant to restricted stock rights (in shares)		8
Restricted stock surrendered for employees' tax liability	(49)			(49)
Restricted stock surrendered for employees' tax liability (in shares)		(4)
Tax benefit associated with employee stock awards	11			11
Stock-based compensation expense related to employee stock options and restricted stock rights	112			112
Dividends ($0.23, $0.20, and $0.19 per common share at December 31, 2015, 2014, and 2013, respectively)	(217)				(217)
Shares repurchased	(5,830)		$ (5,830)
Shares repurchased (in shares)			(429)
Indemnity on tax attributes assumed in connection with the Purchase Transaction	16		$ 16
Balance at Dec. 31, 2013	6,622	$ 0	$ (5,814)	9,682	2,686	68
Balance (in shares) at Dec. 31, 2013		1,132	429
Components of comprehensive income:
Net income	835				835
Other comprehensive income (loss)	(371)					(371)
Issuance of common stock pursuant to employee stock options	172			172
Issuance of common stock pursuant to employee stock options (in shares)		14
Issuance of common stock pursuant to restricted stock rights (in shares)		7
Restricted stock surrendered for employees' tax liability	(66)			(66)
Restricted stock surrendered for employees' tax liability (in shares)		(2)
Tax benefit associated with employee stock awards	30			30
Stock-based compensation expense related to employee stock options and restricted stock rights	106			106
Dividends ($0.23, $0.20, and $0.19 per common share at December 31, 2015, 2014, and 2013, respectively)	(147)				(147)
Indemnity on tax attributes assumed in connection with the Purchase Transaction	52		$ 52
Balance at Dec. 31, 2014	7,233	$ 0	$ (5,762)	9,924	3,374	(303)
Balance (in shares) at Dec. 31, 2014		1,151	429
Components of comprehensive income:
Net income	892				892
Other comprehensive income (loss)	(330)					(330)
Issuance of common stock pursuant to employee stock options	106			106
Issuance of common stock pursuant to employee stock options (in shares)		8
Issuance of common stock pursuant to restricted stock rights (in shares)		7
Restricted stock surrendered for employees' tax liability	(83)			(83)
Restricted stock surrendered for employees' tax liability (in shares)		(3)
Tax benefit associated with employee stock awards	65			65
Stock-based compensation expense related to employee stock options and restricted stock rights	95			95
Dividends ($0.23, $0.20, and $0.19 per common share at December 31, 2015, 2014, and 2013, respectively)	(170)				(170)
Indemnity on tax attributes assumed in connection with the Purchase Transaction	58		$ 58
Shareholder settlement in connection with the Purchase Transaction	202		67	135
Balance at Dec. 31, 2015	$ 8,068	$ 0	$ (5,637)	$ 10,242	$ 4,096	$ (633)
Balance (in shares) at Dec. 31, 2015		1,163	429