FAIR VALUE MEASUREMENTS - Transfers Between Fair Value Levels (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Assets, transfers from level II to level III	$ 4,346,276	$ 126,233
Assets, transfers from level III to level II	367,051	14,570
Assets, transfers from level III to level I	0	1,212,235
Liabilities, transfers from level II to level III	$ 4,272,081	$ 0