Stock-Based Compensation - Narrative (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award
Stock compensation expense	$ 2,485	$ 1,906	$ 1,660
Tax benefits from stock-based compensation	950	728	635
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award
Stock compensation expense	1,276	915	813
Tax benefits from stock-based compensation	488	349	311
Intrinsic value of fully-vested stock options outstanding	1,653
Total intrinsic value of options exercised	1,158	764	757
Tax benefit realized from stock option exercises	397	285	250
Proceeds from stock options exercised	1,612	385	649
Common stock redeemed for payment of stock option exercises, aggregate value	2,675	2,381	1,643
Unrecognized compensation cost related to nonvested restricted stock to be recognized over weighted average period (in years)	1 year 6 months 22 days
Share-Based CompensationaArrangement By Share Based Payment Award, Options, Vested In Period, Fair Value	980
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	1,523
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award
Stock compensation expense	1,209	991	847
Tax benefits from stock-based compensation	462	379	324
Unrecognized compensation cost related to nonvested restricted stock to be recognized over weighted average period (in years)	2 years 1 month 24 days
Stock issued during period, shares, restricted stock award	122,912
Unrecognized compensation cost related to nonvested restricted stock awards	$ 2,081
Restricted Stock \| Upon Achievement of Performance Goals
Share-based Compensation Arrangement by Share-based Payment Award
Stock issued during period, shares, restricted stock award	20,564
Restricted Stock \| Upon Achievement of Defined Return on Asset Performance Goals
Share-based Compensation Arrangement by Share-based Payment Award
Stock issued during period, shares, restricted stock award	10,282
Restricted Stock \| Upon Achievement of Defined Return on Equity Performance Goals
Share-based Compensation Arrangement by Share-based Payment Award
Stock issued during period, shares, restricted stock award	10,282
Restricted Stock \| Upon One-Third Annual Anniversary
Share-based Compensation Arrangement by Share-based Payment Award
Stock issued during period, shares, restricted stock award	102,348
2006 Plan \| Stock Option
Share-based Compensation Arrangement by Share-based Payment Award
Shares available for grant	659,863
2012 Plan \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock award, vesting period	3 years

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