Derivatives Derivatives - Offsetting Arrangements (Loss) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018
Derivative Asset [Abstract]
Fair Market Value	$ 6,958	$ 590
Derivative Asset, gross amounts offset	(1,605)	(276)
Derivative Assets, net amounts of assets	5,353	314
Derivative Liability [Abstract]
Derivative Liability, gross amounts of liabilities	(11,910)	(28,314)
Derivative Liability, gross amounts offset	1,605	276
Derivative Liabilities, net amounts of liabilities	(10,305)	(28,038)
Derivative, net, gross amounts of assets/liabilities	(4,952)	(27,724)
Derivative Assets, Net amounts of assets/liabilities	$ (4,952)	$ (27,724)