Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Derivative asset counterparty credit valuation adjustment	$ 1		$ 2
Fair value, amount transferred from level 1 to level 2	77	$ 37
Fair value, amount transferred from level 2 to level 1	45
Fair value, amount transferred from level 3 to level 2		$ 4
Finance receivables from related party	$ 132		$ 128