Senior Notes and Other Long-Term Debt - Components of Long-Term Debt (Detail) - USD ($)	Jun. 30, 2021	Mar. 31, 2021
Debt Instrument [Line Items]
Finance lease obligations (see Note 1)	$ 53,974,000	$ 56,336,000
Total debt	2,162,409,000	1,854,597,000
Unamortized discount and debt issuance costs	(20,234,000)	(21,441,000)
Less: current portion of long-term debt	30,328,000	30,472,000
Total long-term debt	2,111,847,000	1,802,684,000
2028 Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt	400,000,000	400,000,000
2027 Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt	600,000,000	600,000,000
2025 Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt	700,000,000	700,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt	320,000,000
Ex-Im Credit Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 88,435,000	$ 98,261,000

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Present value of lessee's discounted obligation for lease payments from finance lease.

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