Schedule II — Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Allowance for doubtful accounts receivable
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, Beginning of Year	$ 54	$ 54	$ 54
Additions	0	0	0
Write-offs	0	0	0
Recoveries and Other Adjustments	0	0	0
Balance, End of Year	54	54	54
Deferred tax asset valuation allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, Beginning of Year	315,092	301,393	294,860
Additions	24,585	22,580	9,028
Write-offs	(111,991)	(8,881)	(2,495)
Recoveries and Other Adjustments	0	0	0
Balance, End of Year	$ 227,686	$ 315,092	$ 301,393