Stockholders' Equity (Details 1) - Common Stock - USD ($)	12 Months Ended		264 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Aug. 31, 2014
Stock repurchase program
Dividends paid (in dollars per share)	$ 0	$ 0
Stock repurchased under current and previously announced share repurchase programs			$ 1,200,000,000
Stock repurchased under current and previously announced share repurchase programs (in shares)			6,800,000
2012 Stock Repurchase program
Stock repurchase program
Authorized amount to repurchase shares				$ 20,000,000
Common stock repurchased (in shares)	0	0
Remaining amount available to repurchase shares	$ 11,400,000		$ 11,400,000
Common stock received in lieu of cash from stock option exercises and vesting of non-vested shares (in shares)	3,541
Common stock received in lieu of cash from stock option exercises and vesting of non-vested shares	$ 30,000