Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Number of shares, Beginning balance (in number of shares) at Dec. 31, 2013		495.2
Stockholders' equity, Beginning balance at Dec. 31, 2013	$ 7,302.2		$ 9,868.9	$ 64.6	$ (2,631.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	(334.3)				(334.3)
Other comprehensive loss, net	(78.4)			(78.4)
Issuance of common stock (in number of shares)		17.7
Issuance of common stock	159.1		159.1
Repurchase and retirement of common stock (in number of shares)		(96.7)
Repurchase and retirement of common stock	(2,262.5)		(1,367.0)		(895.5)
Share-based compensation expense	240.0		240.0
Tax effects from employee stock option plans	(21.0)		(21.0)
Payment of cash dividends	(86.0)		(86.0)
Number of shares, Ending balance (in number of shares) at Dec. 31, 2014		416.2
Stockholders' equity, Ending balance at Dec. 31, 2014	4,919.1		8,794.0	(13.8)	(3,861.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	633.7				633.7
Other comprehensive loss, net	(5.4)			(5.4)
Issuance of common stock (in number of shares)		13.6
Issuance of common stock	121.2		121.2
Repurchase and retirement of common stock (in number of shares)		(45.8)
Repurchase and retirement of common stock	(1,153.6)		(639.8)		(513.8)
Share-based compensation expense	217.3		217.3
Tax effects from employee stock option plans	(1.6)		(1.6)
Payment of cash dividends	(156.3)		(156.3)
Number of shares, Ending balance (in number of shares) at Dec. 31, 2015		384.0
Stockholders' equity, Ending balance at Dec. 31, 2015	4,574.4		8,334.8	(19.2)	(3,741.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	592.7				592.7
Other comprehensive loss, net	(18.1)			(18.1)
Issuance of common stock (in number of shares)		11.1
Issuance of common stock	62.3		62.3
Repurchase and retirement of common stock (in number of shares)		(14.0)
Repurchase and retirement of common stock	(324.6)		(191.3)		(133.3)
Share-based compensation expense	222.4		222.4
Tax effects from employee stock option plans	5.9		5.9
Payment of cash dividends	(152.5)		(152.5)
Number of shares, Ending balance (in number of shares) at Dec. 31, 2016		381.1
Stockholders' equity, Ending balance at Dec. 31, 2016	$ 4,962.5		$ 8,281.6	$ (37.3)	$ (3,281.8)