Earnings Per Share (Table Text Block)	3 Months Ended	9 Months Ended
	Dec. 31, 2022	Dec. 31, 2022
Table Text Block Supplement [Abstract]
Schedule Of Earnings Per Share Basic And Diluted [Table Text Block]	For the Quarter Ended     December 31,     2022 2021     (Unaudited)     (In thousands, except share and per share amounts)           Weighted average shares outstanding of Voting Common Stock   19,607,788   19,607,788 Total weighted average shares outstanding for Voting Common Stock and Non-Voting Common Stock   196,077,880   196,077,880 Percent of weighted average shares outstanding of Voting Common Stock   10%   10%           Net earnings available to common stockholders $ 199,244 $ 281,466 Voting Common Stock dividends declared   –   (9,804) Non-Voting Common Stock dividends declared   (7,059)   – Undistributed earnings available to common stockholders $ 192,185 $ 271,662 Undistributed earnings available to common stockholders allocated to Voting Common Stock $ 19,219 $ 27,166           Undistributed earnings per share of Voting Common Stock $ 0.98 $ 1.39 Dividends declared per share of Voting Common Stock $ – $ 0.50 Basic and diluted earnings per share of Voting Common Stock $ 0.98 $ 1.89                     Weighted average shares outstanding of Non-Voting Common Stock   176,470,092   176,470,092 Total weighted average shares outstanding for Voting Common Stock and Non-Voting Common Stock   196,077,880   196,077,880 Percent of weighted average shares outstanding of Non-Voting Common Stock   90%   90%           Net earnings available to common stockholders $ 199,244 $ 281,466 Voting Common Stock dividends declared   –   (9,804) Non-Voting Common Stock dividends declared   (7,059)   – Undistributed earnings available to common stockholders $ 192,185 $ 271,662 Undistributed earnings available to common stockholders allocated to Non-Voting Common Stock $ 172,967 $ 244,496           Undistributed earnings per share of Non-Voting Common Stock $ 0.98 $ 1.39 Dividends declared per share of Non-Voting Common Stock $ 0.04 $ – Basic and diluted earnings per share of Non-Voting Common Stock$ 1.02 $ 1.39	For the Nine Months Ended     December 31,     2022   2021     (Unaudited)     (In thousands, except share and per share amounts)           Weighted average shares outstanding of Voting Common Stock   19,607,788   19,607,788 Total weighted average shares outstanding for Voting Common Stock and Non-Voting Common Stock   196,077,880   196,077,880 Percent of weighted average shares outstanding of Voting Common Stock   10%   10%           Net earnings available to common stockholders $ 885,261 $ 1,036,539 Voting Common Stock dividends declared   (19,608)   (29,412) Non-Voting Common Stock dividends declared   (7,059)   – Undistributed earnings available to common stockholders $ 858,594 $ 1,007,127 Undistributed earnings available to common stockholders allocated to Voting Common Stock $ 85,859 $ 100,713           Undistributed earnings per share of Voting Common Stock $ 4.38 $ 5.14 Dividends declared per share of Voting Common Stock $ 1.00 $ 1.50 Basic and diluted earnings per share of Voting Common Stock $ 5.38 $ 6.64                     Weighted average shares outstanding of Non-Voting Common Stock   176,470,092   176,470,092 Total weighted average shares outstanding for Voting Common Stock and Non-Voting Common Stock   196,077,880   196,077,880 Percent of weighted average shares outstanding of Non-Voting Common Stock   90%   90%           Net earnings available to common stockholders $ 885,261 $ 1,036,539 Voting Common Stock dividends declared   (19,608)   (29,412) Non-Voting Common Stock dividends declared   (7,059)   – Undistributed earnings available to common stockholders $ 858,594 $ 1,007,127 Undistributed earnings available to common stockholders allocated to Non-Voting Common Stock $ 772,735 $ 906,414           Undistributed earnings per share of Non-Voting Common Stock $ 4.38 $ 5.14 Dividends declared per share of Non-Voting Common Stock $ 0.04 $ – Basic and diluted earnings per share of Non-Voting Common Stock$ 4.42 $ 5.14