Stockholders' Equity - Common Stock Repurchased (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Class of Stock [Line Items]
Shares repurchased related to employee stock-based compensation plans	1,365,277	[1]	6,365,002	[1]	4,547,785	[1]
Average purchase price per share	$ 8.93		$ 21.76		$ 15.86
Common shares issued (in shares)	2,013,805	[2]	9,702,976	[2]	6,432,643	[2]
Common Stock [Member]
Class of Stock [Line Items]
Share price (usd per share)	$ 10.19

[1] Comprises shares withheld from stock option exercises and vesting of restricted stock for employees’ tax withholding obligations and shares tendered by employees to satisfy option exercise costs.

[2] Common shares issued under our various compensation and benefit plans.