Employee Benefit Plans - Schedule of Fair Value of Qualified Pension Plan Assets (Details) - Pension plans - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	$ 0	$ 41,517	$ 42,061
Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		741
Significant observable inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		40,776
Significant unobservable inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		0
Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		40,776
Fixed Income Funds | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		0
Fixed Income Funds | Significant observable inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		40,776
Fixed Income Funds | Significant unobservable inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		0
Defined Benefit Plan, Cash and Cash Equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		741
Defined Benefit Plan, Cash and Cash Equivalents | Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		741
Defined Benefit Plan, Cash and Cash Equivalents | Significant observable inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		0
Defined Benefit Plan, Cash and Cash Equivalents | Significant unobservable inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets		$ 0