Postretirement Benefit Plans (Plan Assets at Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Nov. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Scottdale Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 5,302		$ 4,939	$ 5,404
Scottdale Defined Benefit Pension Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	3,891		3,409
Scottdale Defined Benefit Pension Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,411		1,530
Scottdale Defined Benefit Pension Plan [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	670		522
Scottdale Defined Benefit Pension Plan [Member] | Mining [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	43		23
Scottdale Defined Benefit Pension Plan [Member] | Manufacturing [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	870		807
Scottdale Defined Benefit Pension Plan [Member] | Transportation, Communications, Electric, Gas, and Sanitary Services [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	500		555
Scottdale Defined Benefit Pension Plan [Member] | Wholesale Trade [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	23
Scottdale Defined Benefit Pension Plan [Member] | Finance, Insurance, and Real Estate [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,633		17
Scottdale Defined Benefit Pension Plan [Member] | Services [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	145		1,348
Scottdale Defined Benefit Pension Plan [Member] | Other [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets			137
Scottdale Defined Benefit Pension Plan [Member] | Corporate debt securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	7
Scottdale Defined Benefit Pension Plan [Member] | Corporate debt securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,411		$ 1,530
Riverview Defined Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	8,984	$ 8,894
Riverview Defined Benefit Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	8,598
Riverview Defined Benefit Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	386
Riverview Defined Benefit Plan [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	133
Riverview Defined Benefit Plan [Member] | Large-cap Value [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	376
Riverview Defined Benefit Plan [Member] | Large-cap Core [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	382
Riverview Defined Benefit Plan [Member] | Mid-cap Core [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	465
Riverview Defined Benefit Plan [Member] | Small-cap Core [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	306
Riverview Defined Benefit Plan [Member] | International Growth [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	592
Riverview Defined Benefit Plan [Member] | International Value [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	305
Riverview Defined Benefit Plan [Member] | Large Cap Growth [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	727
Riverview Defined Benefit Plan [Member] | Small / Midcap Growth [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	157
Riverview Defined Benefit Plan [Member] | Fixed Income - Core Plus [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	2,020
Riverview Defined Benefit Plan [Member] | Intermediate Duration - Government Credit [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	671
Riverview Defined Benefit Plan [Member] | Long Duration - Government Credit [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,697
Riverview Defined Benefit Plan [Member] | Long U.S. Treasury - ETF [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	767
Riverview Defined Benefit Plan [Member] | Large Cap Value [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 386