Stock Incentive Plans (Details 1) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary of stock options outstanding
Intrinsic value of options exercised in the period	$ 895	$ 69
Stock options:
Number of options, outstanding stock options	538,697	671,294	399,569	315,319
Weighted average exercise price, outstanding stock options	$ 14.66	$ 14.48
Weighted average contractual term of outstanding stock options	6 years 7 months 6 days	6 years 10 months 24 days
Aggregate intrinsic value, outstanding stock options	12,621	3,676
Number of options, exercisable stock options	241,772	283,344
Weighted average exercise price, exercisable stock options	$ 13.60	$ 13.62
Weighted average contractual term of exercisable stock options	4 years 9 months 18 days	4 years 2 months 12 days
Aggregate intrinsic value, exercisable stock options	$ 5,922	$ 1,796

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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