Commitments and Contingencies Rent Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense	$ 139,781	$ 135,850	$ 136,414
Operating Leases, Rent Expense, Sublease Rentals	21,010	21,154	19,672
Operating Leases, Rent Expense, Net	$ 118,771	$ 114,696	$ 116,742