Employee Benefit Plans (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Benefit Plans
Number of officers in employment contract	25
401(k) and Profit Sharing Plans
401(k) and Profit Sharing Plans
Minimum age required to be considered eligible for plan	21
Period of Employment Required to be Eligible for Plan	3
Minimum number of quarters required to be eligible for employer discretionary contribution	1
Minimum number of hours required to be considered eligible for employer discretionary contribution	501
Percent rate for non-elective safe harbor contribution as component of profit sharing plan	3.00%
Profit Sharing Plan Expense	$ 7,107,000	$ 5,862,000	$ 3,974,000
Maximum percentage of annual compensation allowable for contribution by eligible employees	60.00%
Percentage of amount out of first specific percent of employee's contribution matched under plan	50.00%
Percentage of employee's contribution required to determine the matched amount under the plan	6.00%
Employee Benefits Plans
Company's contribution to the plan	2,246,000	1,935,000	1,751,000
Deferred Compensation Plans
Deferred Compensation Plans
Percentage of salary for deferral of cash payments	50.00%
Percentage of bonuses and directors fees for deferral of cash payments	100.00%
Total amount deferred	591,000	376,000	278,000
Liability related to obligations of deferred compensation plans	4,810,000	5,042,000
Employee Benefits Plans
Credit earning rate as a percentage of return on equity	50.00%
Total earnings for the plan	369,000	515,000	231,000
Supplemental Employee Retirement Plan
Employee Benefits Plans
Company's contribution to the plan	151,000	76,000	47,000
Credit earning rate as a percentage of return on equity	50.00%
Total earnings for the plan	$ 59,000	$ 48,000	$ 37,000