Pension and Postretirement Benefits Net Periodic Pension Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Pension and Other Postretirement Benefit Expense [Abstract]
Service cost	$ 526	$ 510	$ 1,555	$ 1,530
Interest expense	1,462	1,693	4,386	5,080
Expected return on plan assets	(1,554)	(1,678)	(4,663)	(5,032)
Amortization of prior service cost	42	48	125	145
Actuarial loss	849	558	2,548	1,672
Curtailment loss	1,062	0	1,062	0
Net periodic pension cost (benefit)	$ 2,387	$ 1,131	$ 5,013	$ 3,395