COMMITMENTS AND CONTINGENT LIABILITIES - Additional Information (Details) $ in Millions, ¥ in Billions	3 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2017 JPY (¥)	Mar. 31, 2017 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Loss contingency accrual, insurance-related assessment, discount rate			4.25%
Loss contingency, discounted amount of insurance-related assessment liability			$ 62
Loss contingency, undiscounted amount of insurance-related assessment liability			94
Loss contingency, insurance-related assessment, discounted amount of premium tax offset			48
Loss contingency, insurance-related assessment, undiscounted amount of premium tax offset			$ 74
Loss contingency, discounted amount of insurance-related assessment liability, payment period (in years)			1
Loss contingency, discounted amount of insurance-related assessment liability, realization period for associated asset offsets (in years)			5
Loss contingency, loss in period			$ 14
Information technology and data services company application maintenance and development services agreement
Commitments And Contingencies Disclosure [Line Items]
Outsourcing agreements, remaining term	5 years	5 years
Outsourcing agreements, aggregate remaining cost	$ 69	¥ 7.8