Pension and Other Post-Retirement Benefit Plans - Schedule of Amount Recognized in Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other changes in plan assets and benefit obligations recognized in OCI, net of tax:
Total recognized in OCI, net of tax	$ (10,675)	$ 901	$ 776
Pension Benefits
Other changes in plan assets and benefit obligations recognized in OCI, net of tax:
Net loss (gain)	(9,674)	1,592	558
Net prior service (credit) cost	0	0	0
Total recognized in OCI, net of tax	(9,674)	1,592	558
Total recognized in net periodic benefit cost and OCI, net of tax	5,564	2,929	1,939
Other Benefits
Other changes in plan assets and benefit obligations recognized in OCI, net of tax:
Net loss (gain)	(974)	(663)	39
Net prior service (credit) cost	(27)	(28)	179
Total recognized in OCI, net of tax	(1,001)	(691)	218
Total recognized in net periodic benefit cost and OCI, net of tax	$ 823	$ 1,192	$ 2,013