Share-Based Compensation Fair Value of Options Granted and Major Assumptions Used (Details) - Stock Options [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value	$ 3.77	$ 6.82	$ 10.11
Risk free interest rate, minimum	0.99%	1.38%	1.31%
Risk free interest rate, maximum	1.15%	1.38%	1.34%
Weighted average risk-free interest rate	1.20%	1.40%	1.30%
Expected price volatility range, minimum	43.42%	36.80%	36.10%
Expected price volatility range, maximum	43.66%	36.80%	37.30%
Weighted average expected price volatility	43.40%	36.80%	37.10%
Expected dividend yield	0.00%	0.37%	0.25%
Expected term in years at the date of grant	4 years 6 months	4 years 6 months	4 years 6 months