COMMITMENTS AND CONTINGENT LIABILITIES - Schedule of Commitment Expiration (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Guarantor Obligations [Line Items]
Total Amounts Committed	$ 732,543
Less Than 1 Year	673,863
1-3 Years	54,612
3-5 Years	3,438
Beyond 5 Years	630
Letters of Credit
Guarantor Obligations [Line Items]
Total Amounts Committed	106,601
Less Than 1 Year	73,046
1-3 Years	33,555
3-5 Years	0
Beyond 5 Years	0
Letters of Credit | Employee-Related
Guarantor Obligations [Line Items]
Total Amounts Committed	73,383
Less Than 1 Year	46,944
1-3 Years	26,439
3-5 Years	0
Beyond 5 Years	0
Letters of Credit | Environmental
Guarantor Obligations [Line Items]
Total Amounts Committed	398
Less Than 1 Year	398
1-3 Years	0
3-5 Years	0
Beyond 5 Years	0
Letters of Credit | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	32,820
Less Than 1 Year	25,704
1-3 Years	7,116
3-5 Years	0
Beyond 5 Years	0
Surety Bonds
Guarantor Obligations [Line Items]
Total Amounts Committed	599,380
Less Than 1 Year	592,183
1-3 Years	7,197
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Employee-Related
Guarantor Obligations [Line Items]
Total Amounts Committed	104,033
Less Than 1 Year	103,083
1-3 Years	950
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Environmental
Guarantor Obligations [Line Items]
Total Amounts Committed	490,545
Less Than 1 Year	484,495
1-3 Years	6,050
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	4,802
Less Than 1 Year	4,605
1-3 Years	197
3-5 Years	0
Beyond 5 Years	0
Guarantees
Guarantor Obligations [Line Items]
Total Amounts Committed	26,562
Less Than 1 Year	8,634
1-3 Years	13,860
3-5 Years	3,438
Beyond 5 Years	630
Guarantees | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	26,562
Less Than 1 Year	8,634
1-3 Years	13,860
3-5 Years	3,438
Beyond 5 Years	$ 630