Pension and Postretirement Benefits Net Periodic Pension Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Pension and Other Postretirement Benefit Expense [Abstract]
Service cost	$ 502	$ 510
Interest expense	1,462	1,693
Expected return on plan assets	(1,554)	(1,677)
Amortization of prior service cost	42	48
Actuarial loss	849	557
Net periodic pension cost (benefit)	$ 1,301	$ 1,131