Employee Benefits - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Prior service credit	$ 0	$ (1,029)
Net actuarial loss	26,013	34,376
Total (Before Tax Effects)	$ 26,013	$ 33,347