Share-Based Compensation (Narrative) (Details) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jan. 31, 2008 1995 Equity Participation Plan [Member]	Dec. 31, 2007 1995 Equity Participation Plan [Member]	May 31, 1995 1995 Equity Participation Plan [Member]	Dec. 31, 2011 Restricted Stock [Member]	Dec. 31, 2010 Restricted Stock [Member]	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2011 Restricted Stock Units (RSUs) [Member] years	Dec. 31, 2011 Restricted Stock And Restricted Stock Units [Member]	Dec. 31, 2010 Restricted Stock And Restricted Stock Units [Member]	Dec. 31, 2011 Maximum [Member] Restricted Stock Units (RSUs) [Member]	Dec. 31, 2011 Common Stock [Member]	Dec. 31, 2010 Common Stock [Member]	Dec. 31, 2009 Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized for issuance						4,944,500
Percentage of stock option exercisable per year				25.00%	20.00%
Stock option expiration period (in years)				10
Cash received from option exercises	$ 1,951,000	$ 733,000	$ 393,000
Share-based compensation expense	899,000	812,000	763,000											439,000	651,000	763,000
Excess tax benefit realized from option exercises	56,000	132,000	5,000
Granted, Shares	0
Number of stock options awarded	0
Intrinsic value of stock options exercised	262,000	431,000	508,000
Total fair value of stock options vested	467,000	498,000	763,000
Unrecognized compensation cost							1,491,000		306,000
Weighted-average period of recognition, in years							2		1.1
Performance period of restricted stock and restricted stock units, vesting years										3
Number of shares granted											80,000	55,000	120,000
Share-based compensation cost	0						460,000	161,000
Tax benefit from compensation cost							$ 161,000	$ 57,000
Targeted number of common share expected to vest										80,000			120,000