COMMITMENTS AND CONTINGENT LIABILITIES - Schedule of Commitment Expiration (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Guarantor Obligations [Line Items]
Total Amounts Committed	$ 746,112
Less Than 1 Year	683,108
1-3 Years	57,633
3-5 Years	4,691
Beyond 5 Years	680
Letters of Credit
Guarantor Obligations [Line Items]
Total Amounts Committed	107,614
Less Than 1 Year	68,450
1-3 Years	39,164
3-5 Years	0
Beyond 5 Years	0
Letters of Credit | Employee-Related
Guarantor Obligations [Line Items]
Total Amounts Committed	74,396
Less Than 1 Year	35,736
1-3 Years	38,660
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	32,316
1-3 Years	504
3-5 Years	0
Beyond 5 Years	0
Surety Bonds
Guarantor Obligations [Line Items]
Total Amounts Committed	609,968
Less Than 1 Year	605,896
1-3 Years	4,072
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Employee-Related
Guarantor Obligations [Line Items]
Total Amounts Committed	105,240
Less Than 1 Year	105,240
1-3 Years	0
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Environmental
Guarantor Obligations [Line Items]
Total Amounts Committed	499,956
Less Than 1 Year	496,371
1-3 Years	3,585
3-5 Years	0
Beyond 5 Years	0
Surety Bonds | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	4,772
Less Than 1 Year	4,285
1-3 Years	487
3-5 Years	0
Beyond 5 Years	0
Guarantees
Guarantor Obligations [Line Items]
Total Amounts Committed	28,530
Less Than 1 Year	8,762
1-3 Years	14,397
3-5 Years	4,691
Beyond 5 Years	680
Guarantees | Other
Guarantor Obligations [Line Items]
Total Amounts Committed	28,530
Less Than 1 Year	8,762
1-3 Years	14,397
3-5 Years	4,691
Beyond 5 Years	$ 680