Significant Accounting Policies Other Comprehensive Income (Loss) - Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Accounting Policies [Abstract]
Actuarial loss	$ 3,629	$ 3,092	$ 4,436
Amortization of prior service cost (credit)	840	(2,213)	(1,369)
Deferred income tax benefit	150	(168)	(189)
Amounts reclassified from accumulated other comprehensive income (loss) to net income (loss)	$ 4,619	$ 711	$ 2,878