Stock Based Compensation Stock Based Compensation (Valuation assumptions) (Details)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield		0.00%	0.00%	0.00%
Expected volatility factor, minimum	[1]	47.00%	49.00%
Expected volatility factor, maximum	[1]	49.00%	51.00%
Expected volatility factor		44.00%		58.00%	[1]
Risk-free interest rate, minimum	[2]	1.80%	1.80%	0.80%
Risk-free interest rate, maximum	[2]	1.90%	2.00%	0.90%
Risk-free interest rate		2.00%
Expected term (in years)	[3]	6 years
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	[3]		6 years	3 years 8 months 12 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	[3]		6 years 6 months	3 years 10 months 24 days

[1] The volatility factor was based on the average volatilities of similar public entities.

[2] The risk-free interest rate was based on the U.S. Treasury yield at the time of grant.

[3] The expected term was derived utilizing the "simplified method" in accordance with Securities and Exchange Commission Staff Accounting Bulletin No. 110, which uses the mid-point between the vesting date and the expiration date of the award. We believe use of this approach is appropriate given the lack of prior history of option exercises upon which to base an expected term.