Interest on Borrowings (Table Text Block)	12 Months Ended
	Mar. 31, 2021
Interest Expense, Borrowings [Abstract]
Components of interest expense	Years Ended March 31,     2021   2020   2019     (In thousands) Interest expense $ 165,484 $ 180,444 $ 150,609 Capitalized interest   (11,573)   (23,517)   (12,733) Amortization of transaction costs   5,949   4,427   3,745 Interest expense resulting from cash flow hedges   3,642   (404)   824 Total interest expense   163,502   160,950   142,445
Interest rates and company borrowings	Revolving Credit Activity       Years Ended March 31,       2021   2020   2019       (In thousands, except interest rates)   Weighted average interest rate during the year   1.40 % 3.31 % 3.39 % Interest rate at year end   1.40 % 2.86 % 3.60 % Maximum amount outstanding during the year $ 1,175,000 $ 1,086,000 $ 959,400   Average amount outstanding during the year $ 1,088,293 $ 1,002,081 $ 699,415   Facility fees $ 261 $ 193 $ 374