Revenue Recognition (Revenue disaggregated by timing of revenue recognition) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Revenues [Abstract]
Total revenues	$ 1,388,558	$ 1,339,514	$ 4,595,156	$ 4,529,682
Insurance premium revenues recognized under ASC 944
Revenues [Abstract]
Total revenues	52,725	50,512	143,693	144,476
Net investment and interest income recognized under other topics
Revenues [Abstract]
Total revenues	40,536	57,457	115,455	186,787
Revenues recognized under ASC 842
Revenues [Abstract]
Total revenues	1,129,821	1,072,028	3,723,458	3,599,867
Revenues recognized under ASC 606
Revenues [Abstract]
Total revenues	165,476	159,517	612,550	598,552
Revenues recognized over time:
Revenues [Abstract]
Total revenues	81,773	73,785	307,740	283,468
Revenues recognized at a point in time:
Revenues [Abstract]
Total revenues	$ 83,703	$ 85,732	$ 304,810	$ 315,084