Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic Earnings Per Share
Net income		$ 76,660,548	$ 117,092,602	$ 276,617,836	$ 204,224,370
Less: Dividends and undistributed earnings allocated to participating securities		1,240,581	1,697,281	4,240,503	2,906,048
Net Income available to common shareholders		$ 75,419,967	$ 115,395,321	$ 272,377,333	$ 201,318,322
Basic weighted average shares outstanding		234,005,573	241,898,117	236,628,999	243,240,699
Net income per share - Basic (in dollars per share)	[1]	$ 0.32	$ 0.48	$ 1.15	$ 0.83
Diluted Earnings Per Share
Allocation of Net Income used in basic computation		$ 75,419,967	$ 115,395,321	$ 272,377,333	$ 201,318,322
Reallocation of undistributed earnings		2,943	4,742	13,289	6,731
Net Income available to common shareholders - Diluted		$ 75,422,910	$ 115,400,063	$ 272,390,622	$ 201,325,053
Number of shares used in basic computation		234,005,573	241,898,117	236,628,999	243,240,699
Additional weighted average dilutive common stock equivalents (in shares)		897,636	918,950	1,108,216	1,026,916
Diluted weighted average shares outstanding		234,903,209	242,817,067	237,737,215	244,267,615
Net Income per share - Diluted (in dollars per share)	[1]	$ 0.32	$ 0.48	$ 1.15	$ 0.82
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive		987,757	412,775	180,669	412,775

[1] (1) Earnings Per Share has been adjusted to exclude the portion of net income allocated to participating securities as a result of share-based payment awards.