Stock-Based Compensation (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Estimated fair value at date of grant of options for common stock granted
Weighted-average grant date fair value of options for our common stock granted during the year, per share	$ 6.28	$ 5.71	$ 4.56
Weighted-average assumptions:
Dividend yield	3.60%	2.60%	1.60%
Volatility	34.60%	39.00%	60.80%
Risk-free interest rate	2.80%	3.00%	2.30%
Expected life (years)	6.5	6.5	6.5