Stock Options and Restricted Stock (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Weighted-average grant date fair values of options granted
Cash received from option exercises	$ 781,000	$ 3,339,000	$ 1,455,000
Total tax benefits realized for tax deductions from options exercised	405,000	1,025,000	233,000
Total intrinsic value of options exercised	1,468,000	4,240,000	1,238,000
Fair value of shares vested	310,000	315,000	1,245,000
Aggregate intrinsic value of vested shares outstanding	$ 13,393,000	$ 11,288,000	$ 8,961,000