Stock Based Compensation Fair Value Assumptions for Stock Options (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Two-Year Bonus Stock Options [Member]
Risk-free interest rate			2.29%
Expected volatility			45.70%
Expected term (in years)			4 years 6 months
Weighted average grant date fair value of options granted during the period			$ 5.31
Five Year Service Stock Options [Member]
Risk-free interest rate	0.82%	2.39%	2.29%
Expected volatility	53.08%	48.00%	45.70%
Expected term (in years)	5 years 6 months	5 years 6 months	5 years 6 months
Weighted average grant date fair value of options granted during the period	$ 5.85	$ 6.58	$ 5.84