Employee Benefit Plan (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Discretionary contribution shares	90,876	84,333	107,728
Value of contributed shares	$ 2,469,000	$ 2,045,000	$ 1,835,000
Contributed cash		200,000	200,000
Total compensation expense	$ 2,500,000	$ 2,200,000	$ 2,000,000