Earnings Per Share Calculation Basic Diluted Earnings Per Share Voting Non Voting Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share Diluted Other Disclosures [Abstract]
Percent Weighted Average Shares Outstanding Common Stock	10.00%	10.00%	10.00%	10.00%
Net earnings available to common shareholders	$ 186,798	$ 273,508	$ 382,215	$ 530,346
Non-Voting Common Stock dividends declared			(17,647)	(14,118)
Undistributed earnings available to common stockholders			$ 36,457	$ 51,623
Undistributed earnings per share, common stock			$ 1.86	$ 2.63
Common Stock [Member]
Earnings Per Share Diluted Other Disclosures [Abstract]
Weighted Average Number Of Shares Outstanding Basic	19,607,788	19,607,788	19,607,788	19,607,788
Percent Weighted Average Shares Outstanding Common Stock	10.00%	10.00%	10.00%	10.00%
Non-Voting Common Stock dividends declared	$ (8,823)	$ (7,059)
Undistributed earnings available to common stockholders	177,975	266,449	$ 364,568	$ 516,228
Undistributed earnings available to common stockholders, participating securities	$ 17,798	$ 26,645
Undistributed earnings per share, common stock	$ 0.91	$ 1.36
Income Loss From Continuing Operations Per Basic Share, Total	$ 0.91	$ 1.36	$ 1.86	$ 2.63
Nonvoting Common Stock [Member]
Earnings Per Share Diluted Other Disclosures [Abstract]
Weighted Average Number Of Shares Outstanding Basic	176,470,092	176,470,092	176,470,092	176,470,092
Percent Weighted Average Shares Outstanding Common Stock	90.00%	90.00%	90.00%	90.00%
Net earnings available to common shareholders	$ 186,798	$ 273,508	$ 382,215	$ 530,346
Non-Voting Common Stock dividends declared	(8,823)	(7,059)	(17,647)	(14,118)
Undistributed earnings available to common stockholders	177,975	266,449	364,568	516,228
Undistributed earnings available to common stockholders, participating securities	$ 160,178	$ 239,804	$ 328,111	$ 464,605
Undistributed earnings per share, common stock	$ 0.91	$ 1.36	$ 1.86	$ 2.63
Dividends declared per share, distributed	0.05	0.04	0.1	0.08
Income Loss From Continuing Operations Per Basic Share, Total	$ 0.96	$ 1.4	$ 1.96	$ 2.71
Nonvoting Common Stock [Member] | Common Stock [Member]
Earnings Per Share Diluted Other Disclosures [Abstract]
Weighted Average Number Of Shares Outstanding Basic	196,077,880	196,077,880	196,077,880	196,077,880