Employee Benefit Plans - Additional Information (Details) - USD ($)	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Supplemental executive retirement plan	$ 12,218,000	$ 11,337,000
Supplemental Executive Retirement Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Supplemental executive retirement plan	12,200,000	$ 11,300,000
Employer contributions to benefit plans	$ 0