Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Basic earnings per share:
Net income	$ 130,811	$ 176,934	$ 294,663	$ 496,653
Weighted average common shares outstanding - basic (in shares)	338,598	351,475	340,408	354,272
Basic earnings per share (in dollars per share)	$ 0.39	$ 0.50	$ 0.87	$ 1.40
Diluted earnings per share:
Net income	$ 130,811	$ 176,934	$ 294,663	$ 496,653
Diluted income available to common shareholders	$ 134,972	$ 181,500	$ 307,956	$ 510,351
Weighted average common shares outstanding - basic (in shares)	338,598	351,475	340,408	354,272
Effect of dilutive securities:
Weighted average common shares outstanding - diluted (in shares)	357,195	372,575	360,389	375,266
Diluted earnings per share (in dollars per share)	$ 0.38	$ 0.49	$ 0.85	$ 1.36
9% Convertible Junior Subordinated Debentures
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Stated interest rate	9.00%		9.00%
Diluted earnings per share:
Dilutive securities	$ 4,161	$ 4,566	$ 13,293	$ 13,698
Effect of dilutive securities:
Dilutive securities (in shares)	17,220	19,028	18,489	19,028
Unvested RSUs
Effect of dilutive securities:
Unvested RSUs (in shares)	1,377	2,072	1,492	1,966

Contractual interest rate for funds borrowed, under the debt agreement.

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