Derivatives (Narratives) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable To Parent [Abstract]
Interest expense	$ 223,958	$ 167,424	$ 163,502
Derivative Fair Value Of Derivative Net [Abstract]
Derivative hedges, net market value	5,311	0		$ 4,300	$ 7,500
Derivative hedges, notional amount				$ 465,700	$ 416,700
Amounts reclassified from AOCI to interest expense	772	(3,948)	(3,640)
Interest rate contracts
AOCI Attributable To Parent [Abstract]
Interest expense	3,700
Investments, other
Derivative Fair Value Of Derivative Net [Abstract]
Amounts reclassified from AOCI to interest expense	$ 8,900	$ 3,700	$ 2,600