Pension and Other Post-retirement Benefit Plans - Amounts in Financial Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Future Amortization of Gain (Loss)	$ 460
Defined Benefit Plan Accumulated Other Comprehensive Income (Loss) Tax	2,000	$ 2,300
Amortization:
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)	85
Pension
Amounts recognized in the Consolidated Balance Sheets
Current liability	(833)	(626)
Noncurrent liability	(34,615)	(38,233)
Amount recognized, end of year	(35,448)	(38,859)
Accumulated other comprehensive income (loss)
Net actuarial loss (gain)	15,585	21,408
Prior service cost	1,582	1,300
Accumulated other comprehensive (income) loss	17,167	22,708
Components of benefit costs (credit)
Net service cost	1,507	1,286	$ 1,308
Interest cost	1,347	1,819	1,734
Expected return on plan assets	(433)	(499)	(486)
Amortization:
Actuarial (gain) loss	704	277	318
Prior service cost	60	17	4
Net periodic benefit cost (credit)	3,185	2,900	2,878
Other Benefits
Amounts recognized in the Consolidated Balance Sheets
Current liability	(82)	(97)
Noncurrent liability	(541)	(749)
Amount recognized, end of year	(623)	(846)
Accumulated other comprehensive income (loss)
Net actuarial loss (gain)	(1,114)	(1,159)
Prior service cost	0	0
Accumulated other comprehensive (income) loss	(1,114)	(1,159)
Components of benefit costs (credit)
Net service cost	0	0	0
Interest cost	19	29	23
Expected return on plan assets	0	0	0
Amortization:
Actuarial (gain) loss	(191)	(187)	(259)
Prior service cost	0	0	0
Net periodic benefit cost (credit)	$ (172)	$ (158)	$ (236)