Leases (Maturities of lease liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020
Finance Lease Liabilities Payments Due [Abstract]
2021	$ 190,770
2022	144,558
2023	123,094
2024	86,571
2025	48,711
Thereafter	12,389
Total lease payments	606,093
Less: imputed interest	(44,742)
Financing lease liability	561,351
Operating Lease Liabilities Payments Due [Abstract]
2021	24,267
2022	22,367
2023	21,339
2024	13,767
2025	4,809
Thereafter	63,677
Total lease payments	150,226
Less: inputed interest	(53,002)
Operating lease liability	$ 97,224	$ 106,443