Earnings Per Share Calculation Basic Diluted Earnings Per Share Voting Non Voting Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share Diluted Other Disclosures [Abstract]
Net earnings available to common shareholders	$ 195,417	$ 256,838
Common Stock [Member]
Earnings Per Share Diluted Other Disclosures [Abstract]
Weighted Average Number Of Shares Outstanding Basic	19,607,788	19,607,788
Percent Weighted Average Shares Outstanding Common Stock	10.00%	10.00%
Non-Voting Common Stock dividends declared	$ (8,824)	$ (7,059)
Undistributed earnings available to common stockholders	186,593	249,779
Undistributed earnings available to common stockholders, participating securities	$ 18,659	$ 24,978
Undistributed earnings per share, common stock	$ 0.95	$ 1.27
Income Loss From Continuing Operations Per Basic Share, Total	$ 0.95	$ 1.27
Nonvoting Common Stock [Member]
Earnings Per Share Diluted Other Disclosures [Abstract]
Weighted Average Number Of Shares Outstanding Basic	176,470,092	176,470,092
Percent Weighted Average Shares Outstanding Common Stock	90.00%	90.00%
Non-Voting Common Stock dividends declared	$ (8,824)	$ (7,059)
Undistributed earnings available to common stockholders	186,593	249,779
Undistributed earnings available to common stockholders, participating securities	$ 167,934	$ 224,801
Undistributed earnings per share, common stock	$ 0.95	$ 1.27
Dividends declared per share, distributed	0.05	0.04
Income Loss From Continuing Operations Per Basic Share, Total	$ 1	$ 1.31
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