Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands		1 Months Ended	11 Months Ended	12 Months Ended
	May 08, 2019	Apr. 30, 2016 shares	Mar. 31, 2020 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) installment $ / shares shares	Mar. 31, 2019 USD ($) $ / shares shares	Mar. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock split ratio	0.125		0.125
Number of shares available for future issuance (in shares)					8,400,000
Number of shares available for future issuance (in shares)			4,000,000	4,000,000
Number of options outstanding, before stock split (in shares)					15,400,000
Number of options outstanding (in shares)			2,008,735	2,008,735	1,919,158	1,760,602
Exercise price of options (in dollars per share) | $ / shares			$ 14.39	$ 14.39	$ 34.09	$ 44.11
Number of options granted (in shares)				1,541,672	606,599
Options granted, weighted average exercise price (in dollars per share) | $ / shares				$ 8.12	$ 16.41
Common Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options vested (in shares)				500,000
Share-based Payment Arrangement, Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to options | $			$ 8,900	$ 8,900
Remaining weighted-average service period				2 years 4 months 10 days
Time-Based Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Vesting percentage				25.00%
Number of installments | installment				12
Market-Based Performance Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)			400,000	400,000
Exercise price of options (in dollars per share) | $ / shares			$ 10.66	$ 10.66
Number of options granted (in shares)				400,000	100,000
Options granted, weighted average exercise price (in dollars per share) | $ / shares				$ 8.07	$ 20.49
Options granted, estimated grant date fair value | $				$ 1,200	$ 1,500
Number of options vested (in shares)				19,000
Options vested, weighted average exercise price (in dollars per share) | $ / shares				$ 11.68
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)			247,863	247,863	0
Number of options granted (in shares)				369,577
Aggregate grant date intrinsic value | $				$ 2,800
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance before split (in shares)					24,800,000
Shares authorized for issuance (in shares)					3,100,000
Number of shares available for future issuance (in shares)			1,500,000	1,500,000	1,000,000
2015 Equity Incentive Plan | Share-based Payment Arrangement, Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted (in shares)				1,500,000	600,000
Options granted, weighted average exercise price (in dollars per share) | $ / shares				$ 8.12	$ 16.41
Options granted, estimated grant date fair value | $				$ 7,600	$ 6,300
Grants To Directors And Employees | Share-based Payment Arrangement, Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $				7,000	17,700
RSL, RSG and RSI Employees | RSL
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $				45	(2,600)
Employees | RSL
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $				$ 900	$ 1,300
Shankar Ramaswamy
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted (in shares)		5,375