CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Millions, unless otherwise specified	Total	Common stock:	Additional paid-in capital:	Accumulated losses:	Treasury stock:	Accumulated other comprehensive (loss) income:
Beginning balance at Dec. 31, 2011		$ 1.0	$ 693.6	$ (143.6)	$ (74.5)	$ (32.8)
Change in the number of shares of Class A common stock outstanding [Roll Forward]
Issuance of Class A common stock in connection with employee stock purchase plan		0	0.6
Net issuance and redemption of Class A common stock in connection with stock options, RSUs and warrants		0	(4.3)
Purchases of Class A common stock		0			(68.4)
Stock-based compensation			24.2
Tax effect from employee stock options and RSUs			(1.5)
Deferred compensation			3.3
Net loss				(62.6)
Other comprehensive (loss) income	29.8					29.8
Ending balance at Dec. 31, 2012	364.8	1.0	715.9	(206.2)	(142.9)	(3.0)
Change in the number of shares of Class A common stock outstanding [Roll Forward]
Issuance of Class A common stock in connection with employee stock purchase plan		0	0.7
Net issuance and redemption of Class A common stock in connection with stock options, RSUs and warrants		0	(0.9)
Purchases of Class A common stock		0			(2.8)
Stock-based compensation			21.8
Tax effect from employee stock options and RSUs			0.3
Deferred compensation			0
Net loss				(30.2)
Other comprehensive (loss) income	21.3					21.3
Ending balance at Dec. 31, 2013	375.0	1.0	737.8	(236.4)	(145.7)	18.3
Change in the number of shares of Class A common stock outstanding [Roll Forward]
Issuance of Class A common stock in connection with employee stock purchase plan		0	1.6
Net issuance and redemption of Class A common stock in connection with stock options, RSUs and warrants		0	(20.6)
Purchases of Class A common stock		0			(29.5)
Stock-based compensation			24.1
Tax effect from employee stock options and RSUs			0.3
Deferred compensation			0
Net loss				(234.3)
Other comprehensive (loss) income	(112.7)					(112.7)
Ending balance at Dec. 31, 2014	$ 3.9	$ 1.0	$ 743.2	$ (470.7)	$ (175.2)	$ (94.4)