Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Basic earnings per share [Abstract]
Net income	$ 634,983	$ 446,093	$ 673,763
Weighted average common shares outstanding - basic (in shares)	334,330	339,953	352,827
Basic earnings per share (in dollars per share)	$ 1.90	$ 1.31	$ 1.91
Diluted earnings per share [Abstract]
Net income	$ 634,983	$ 446,093	$ 673,763
Diluted income available to common shareholders	$ 649,326	$ 463,097	$ 692,027
Weighted-average shares - basic (in shares)	334,330	339,953	352,827
Effect of dilutive securities [Abstract]
Weighted-average shares - diluted (in shares)	351,308	359,293	373,924
Diluted income per share (in dollars per share)	$ 1.85	$ 1.29	$ 1.85
Federal statutory income tax rate (in hundredths)	21.00%	21.00%	21.00%
9% Convertible Junior Subordinated Debentures due 2063
Diluted earnings per share [Abstract]
Dilutive securities	$ 14,343	$ 17,004	$ 18,264
Effect of dilutive securities [Abstract]
Dilutive securities (in shares)	15,196	17,751	19,028
Stated interest rate (in hundredths)	9.00%	9.00%	9.00%
Unvested Restricted Stock Units
Effect of dilutive securities [Abstract]
Dilutive securities - Share based compensation (in shares)	1,782	1,589	2,069