Employee Benefit Plans - Schedule of Fair Value of Qualified Pension Plan Assets (Details) - Pension plans - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	$ 42,061	$ 43,603	$ 48,656
Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	4,045	5,614
Fixed income funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	37,527	36,954
Cash/cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	489	1,035
Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	489	1,035
Quoted prices in active markets for identical assets (Level 1) | Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Quoted prices in active markets for identical assets (Level 1) | Fixed income funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Quoted prices in active markets for identical assets (Level 1) | Cash/cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	489	1,035
Significant observable inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	41,572	42,568
Significant observable inputs (Level 2) | Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	4,045	5,614
Significant observable inputs (Level 2) | Fixed income funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	37,527	36,954
Significant observable inputs (Level 2) | Cash/cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3) | Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3) | Fixed income funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3) | Cash/cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	$ 0	$ 0