Stockholders' Equity - Common stock repurchased (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Equity [Abstract]
Shares repurchased related to employee stock-based compensation plans	358,771	[1]	3,040,788	[1]	358,771	[1]	5,365,363	[1]
Average purchase price per share	$ 8.62		$ 22.35		$ 8.62		$ 20.51
Common shares issued	504,929	[2]	4,115,424	[2]	504,929	[2]	8,273,219	[2]

[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.