Accumulated other comprehensive loss 2 of 2 (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized investment gain (loss) at beginning of year	$ 626
Other comprehensive income (loss) before reclassification	(4,376)
Amounts reclassified from other comprehensive loss to net income	1,659
Net unrealized investment gain at end of year	694	$ 626
Unrealized Investment Gain
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized investment gain (loss) at beginning of year	626	859	$ 1,768
Other comprehensive income (loss) before reclassification	173	(79)	433
Amounts reclassified from other comprehensive loss to net income	(105)	(154)	(1,342)
Net change in unrealized gain (loss) on investments	68	(233)	(909)
Net unrealized investment gain at end of year	$ 694	$ 626	$ 859