Income Taxes (Reconciliation of Effective Tax Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income tax provision at statutory rate	$ 37,480	$ 38,798	$ 55,015
Income tax provision at statutory rate (as percent)	35.00%	35.00%	35.00%
Foreign tax benefit	$ (2,084)	$ (2,322)	$ (2,894)
Foreign tax benefit provision (as percent)	(1.90%)	(2.10%)	(1.80%)
State income taxes, net of federal income tax benefit	$ 1,414	$ 1,820	$ 3,284
State income taxes, net of federal income tax benefit (as percent)	1.30%	1.70%	2.00%
Impact of tax legislation	$ (268,244)	$ 0	$ 0
Impact of tax (as percent)	(250.50%)	0.00%	0.00%
Goodwill adjustment for sale of asset	$ 0	$ 3,208	$ 0
Goodwill adjustment for sale of asset (as percent)	0.00%	2.90%	0.00%
Nondeductible transaction costs	$ 0	$ 686	$ 1,071
Nondeductible transaction costs (as percent)	0.00%	0.60%	0.70%
Nondeductible compensation	$ 0	$ 342	$ 758
Nondeductible compensation (as percent)	0.00%	0.30%	0.50%
Other	$ (1,050)	$ (1,077)	$ 44
Other (as percent)	(1.00%)	(1.00%)	0.00%
Total (benefit) provision for income taxes	$ (232,484)	$ 41,455	$ 57,278
Total provision for income taxes (as percent)	(217.10%)	37.40%	36.40%