Employee Benefits - (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Wage Base	$ 260,000	$ 255,000	$ 250,000
Deferred Compensation Arrangement with Individual, Requisite Service Period	3 years
Defined Contribution Plan, Cost Recognized	$ 1,200,000	$ 1,100,000	$ 900,000
Base Percentage [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contribution percentage to retirement plan	13.20%
Excess Percentage for amounts above Social Security taxable wage base] [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contribution percentage to retirement plan	5.70%