Employee Benefit Plans Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 Months	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Eligibility period for 401K savings plan, number of months	3
Defined Contribution Plan, Contributions by Employee, Percent	60.00%
Defined Contribution Plan, Employer Matching Contribution	$ 0.50
Defined Contribution Plan, Employer Matching Contribution, Percent	10.00%
Defined Contribution Plan, Cost Recognized	700,000	600,000	500,000
Deferred Compensation, Employee Salary, Percent	70.00%
Deferred Compensation, Directors Fees and Employee Bonuses, Percent	100.00%
Deferred Compensation Arrangement with Individual, Employer Contribution, Percent	10.00%
Fair Value (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred Compensation Liability, Current and Noncurrent	$ 7,339,000	$ 5,597,000