Segment Information - Revenue Information by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 1,594,625	$ 1,559,337	$ 1,417,431
United States [Member]
Segment Reporting Information [Line Items]
Total revenues	1,403,473	1,352,002	1,207,651
Europe, the Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Total revenues	85,704	85,828	80,202
Asia, Pacific [Member]
Segment Reporting Information [Line Items]
Total revenues	72,465	88,888	79,213
North America other than United States [Member]
Segment Reporting Information [Line Items]
Total revenues	18,777	24,649	38,957
Central and Latin America [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 14,206	$ 7,970	$ 11,408