Stock Based Compensation Fair Value Assumptions for Stock Options (Details) (Five Year Service Stock Options [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Five Year Service Stock Options [Member]
Risk-free interest rate	1.75%	0.88%	0.82%
Expected volatility	57.99%	56.70%	53.08%
Expected term (in years)	5 years 7 months	5 years 6 months	5 years 6 months
Weighted average grant date fair value of options granted during the period	$ 12.64	$ 11.97	$ 5.85