Income Taxes (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Taxes [Abstract]
Net operating losses or credits utilization period	1 year
Change in cumulative ownership percentage (in hundredths)	50.00%
Period with in which cumulative ownership change	3 years
Gross unrecognized tax benefits	$ 16,400,000
Unrecognized tax benefits interest and penalties	0
Unrecognized tax benefits accrued interest and penalties	0
Federal income tax benefit or expense	$ 0	$ 0