Benefit Plans Reconciliation of Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	$ 133,459
Fair value of assets at end of year	260,747	$ 133,459
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	187,877	196,207
Service cost	5,947	5,790	$ 4,699
Interest cost	8,506	6,879	6,993
Defined Benefit Plan, Benefit Obligation, Business Combination	108,162	0
Expected return on assets	10,118	9,255	7,888
Actuarial loss	35,502	(14,447)
Implicit rate subsidy	0	0
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	0	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change	(10)	0
Benefits paid	(7,744)	(6,552)
Benefit obligation at end of year	338,240	187,877	196,207
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	127,610	133,360
Actual return on plan assets	34,807	(7,700)
Defined Benefit Plan, Plan Assets, Business Combination	79,382	0
Employer contributions	9,476	8,502
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	0	0
Defined Benefit Plan, Plan Assets, Period Increase (Decrease)	(10)	0
Benefits paid	(7,744)	(6,552)
Fair value of assets at end of year	243,521	127,610	133,360
Funded status at end of year	(94,719)	(60,267)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	17,489	18,003
Service cost	581	616	529
Interest cost	775	627	634
Defined Benefit Plan, Benefit Obligation, Business Combination	12,537	0
Expected return on assets	475	450	376
Actuarial loss	2,027	(988)
Implicit rate subsidy	(217)	(207)
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	85	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change	0	0
Benefits paid	(731)	(562)
Benefit obligation at end of year	32,546	17,489	18,003
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	5,849	6,804
Actual return on plan assets	1,972	(262)
Defined Benefit Plan, Plan Assets, Business Combination	9,314	0
Employer contributions	738	629
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	85	0
Defined Benefit Plan, Plan Assets, Period Increase (Decrease)	(55)	0
Benefits paid	(677)	(1,322)
Fair value of assets at end of year	17,226	5,849	$ 6,804
Funded status at end of year	$ (15,320)	$ (11,640)