Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Reconciliation of gross unrecognized tax benefits (excluding interest and penalties)
Beginning of fiscal year	$ 7,390	$ 7,103	$ 6,377
Additions from business combinations	1,270	0	0
Additions for tax positions of the current year	1,078	762	763
Reductions for tax positions of prior years	(1,058)	(64)	0
Lapse in statute of limitations	0	(411)	(10)
Settlements	0	0	(27)
End of fiscal year	$ 8,680	$ 7,390	$ 7,103