Leases (Maturities of lease liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Finance Lease Liabilities Payments Due [Abstract]
2020	$ 246,596
2021	184,010
2022	143,983
2023	122,112
2024	83,369
Thereafter	81,681
Total lease payments	861,751
Less: imputed interest	0
Financing lease liability	861,751
Operating Lease Liabilities Payments Due [Abstract]
2020	21,776
2021	19,336
2022	18,298
2023	17,607
2024	13,545
Thereafter	70,411
Total lease payments	160,973
Less: inputed interest	(56,141)
Operating lease liability	$ 104,832	$ 0