Commitments and Contingent Liabilities (Schedule of Commitment Expiration) (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Guarantor Obligations [Line Items]
Total Amounts Committed	$ 744,585
Less Than 1 Year	651,071
1-3 Years	92,734
3-5 Years	398
Beyond 5 Years	382
Letters of Credit
Guarantor Obligations [Line Items]
Total Amounts Committed	110,799
Less Than 1 Year	61,559
1-3 Years	49,240
3-5 Years	0
Beyond 5 Years	0
Letters of Credit | Employee-Related
Guarantor Obligations [Line Items]
Total Amounts Committed	64,558
Less Than 1 Year	50,416
1-3 Years	14,142
3-5 Years	0
Beyond 5 Years	0
Letters of Credit | Environmental
Guarantor Obligations [Line Items]
Total Amounts Committed	398
Less Than 1 Year	0
1-3 Years	398
3-5 Years	0
Beyond 5 Years	0
Letters of Credit | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	45,843
Less Than 1 Year	11,143
1-3 Years	34,700
3-5 Years	0
Beyond 5 Years	0
Surety Bonds
Guarantor Obligations [Line Items]
Total Amounts Committed	618,251
Less Than 1 Year	582,650
1-3 Years	35,601
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Employee-Related
Guarantor Obligations [Line Items]
Total Amounts Committed	87,424
Less Than 1 Year	86,124
1-3 Years	1,300
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Environmental
Guarantor Obligations [Line Items]
Total Amounts Committed	526,838
Less Than 1 Year	492,696
1-3 Years	34,142
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	3,989
Less Than 1 Year	3,830
1-3 Years	159
3-5 Years	0
Beyond 5 Years	0
Guarantees
Guarantor Obligations [Line Items]
Total Amounts Committed	15,535
Less Than 1 Year	6,862
1-3 Years	7,893
3-5 Years	398
Beyond 5 Years	382
Guarantees | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	15,535
Less Than 1 Year	6,862
1-3 Years	7,893
3-5 Years	398
Beyond 5 Years	$ 382