Accrued Liabilities and Other Non-current Liabilities Accrued Liabilities (Narrative) (Details) - USD ($)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition [Line Items]
Other non-current liabilities	$ 223,966,000	$ 212,783,000
Profit Sharing Payable	$ 14,103,000