Retirement Benefit Plans (Fair Values of Pension Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Total Assets including Common Trust Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 859,883	$ 815,304
Level 1 [Member] | Total Assets including Common Trust Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	455,917	417,127
Level 2 [Member] | Total Assets including Common Trust Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40,254	43,076
Pension Benefits [Member] | Cash And Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,280	3,778
Pension Benefits [Member] | Total Cash and Cash-Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,280	3,778
Pension Benefits [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69,941	72,603
Pension Benefits [Member] | Mutual Fund-Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20,428	22,087
Pension Benefits [Member] | Exchange Traded Fund (ETF)-Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,049	3,750
Pension Benefits [Member] | Total Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	94,418	98,440
Pension Benefits [Member] | Domestic And Foreign Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	109,610	97,966
Pension Benefits [Member] | Mutual Funds-Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	270,863	260,019
Pension Benefits [Member] | Total Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	380,473	357,985
Pension Benefits [Member] | Total Real Assets At Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	496,171	460,203
Pension Benefits [Member] | Common Trust Fund (Fixed Income) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	294,112	298,694
Pension Benefits [Member] | Common Trust Fund (Real Assets) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69,600	56,407
Pension Benefits [Member] | Level 1 [Member] | Cash And Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,280	3,778
Pension Benefits [Member] | Level 1 [Member] | Total Cash and Cash-Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,280	3,778
Pension Benefits [Member] | Level 1 [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,687	29,527
Pension Benefits [Member] | Level 1 [Member] | Mutual Fund-Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20,428	22,087
Pension Benefits [Member] | Level 1 [Member] | Exchange Traded Fund (ETF)-Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,049	3,750
Pension Benefits [Member] | Level 1 [Member] | Total Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54,164	55,364
Pension Benefits [Member] | Level 1 [Member] | Domestic And Foreign Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	109,610	97,966
Pension Benefits [Member] | Level 1 [Member] | Mutual Funds-Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	270,863	260,019
Pension Benefits [Member] | Level 1 [Member] | Total Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	380,473	357,985
Pension Benefits [Member] | Level 1 [Member] | Total Real Assets At Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	455,917	417,127
Pension Benefits [Member] | Level 2 [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40,254	43,076
Pension Benefits [Member] | Level 2 [Member] | Total Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40,254	43,076
Pension Benefits [Member] | Level 2 [Member] | Total Real Assets At Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 40,254	$ 43,076