Stock-Based Compensation Black-Scholes pricing model (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2014
Black-Scholes pricing model [Abstract]
Risk-free interest rate	0.011	0.06% - 1.4%
Expected volatility	0.50%	0.40%
Expected term (in years)	4	0.78 - 4