Income Taxes Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	34.00%	34.00%	34.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent	7.70%	(1.20%)	(0.90%)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent	(41.10%)	(34.90%)	(32.50%)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent	(1.20%)	1.40%	(0.50%)
Effective income tax rate	(0.60%)	(0.70%)	0.10%