Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Participant's eligible compensation	Under the plan, the Company will match 75% of the first 4% of each employee's contributions not to exceed 3% of that employee's eligible compensation
Defined contribution plan, matching expense	$ 1,043	$ 968	$ 886
Incentive Bonus Plans [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Incentive bonus plan expense	7,874	5,030	3,291
Deferred Bonus Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan, matching expense	15	11	7
Deferred plan amendments	Company sponsors a deferred bonus plan, which permits certain employees to defer receipt of up to 100% of their annual incentive bonus for three, five or ten years. Under the plan, the Company will match 10% of the amount deferred and the match vests after three years.
Deferred bonus plan, deferred expenses	$ 960	$ 750
Deferred Compensation Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred plan amendments	Company initiated a deferred compensation plan, which permits certain employees to defer up to 50% of their annual base pay until retirement. Upon retirement, the employee can elect a lump sum distribution or annual payments over two to ten years.