GUARANTEES (Details) $ in Millions	Mar. 31, 2018 USD ($)
Guarantees
Total guarantees	$ 100.4
Guarantees expiring in less than 1 year	64.3
Guarantees expiring within 1 to 3 years	25.5
Guarantees with expiration over 3 years	10.6
Commodity transactions guarantee
Guarantees
Total guarantees	8.1
Guarantees expiring in less than 1 year	8.1
Guarantees expiring within 1 to 3 years	0.0
Guarantees with expiration over 3 years	0.0
Standby letters of credit
Guarantees
Total guarantees	71.4
Guarantees expiring in less than 1 year	46.0
Guarantees expiring within 1 to 3 years	25.4
Guarantees with expiration over 3 years	0.0
Surety bonds
Guarantees
Total guarantees	9.8
Guarantees expiring in less than 1 year	9.7
Guarantees expiring within 1 to 3 years	0.1
Guarantees with expiration over 3 years	0.0
Other guarantees
Guarantees
Total guarantees	11.1
Guarantees expiring in less than 1 year	0.5
Guarantees expiring within 1 to 3 years	0.0
Guarantees with expiration over 3 years	10.6
Other indemnifications
Guarantees
Total guarantees	11.1
Liability related to workers compensation coverage	10.6
Non-Utility Energy Infrastructure | Commodity transactions guarantee
Guarantees
Total guarantees	$ 8.1