Parent Company Only Financial Information, Statement of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income
Interest income on notes receivable from subsidiaries	$ 693,729	$ 785,241	$ 998,099
Total revenue	1,058,219	1,277,012	1,216,498
Expense
Income before income tax expense	436,307	326,972	406,509
Income tax expense	85,313	20,200	79,720
Net income	350,994	306,771	326,790
Preferred stock dividends	17,111	18,358	15,202
Net income available to common equity	333,883	288,413	311,587
Parent Company Only
Income
Income from subsidiaries	361,198	317,895	341,789
Interest income on notes receivable from subsidiaries	3,247	3,257	13,983
Other income	682	933	761
Total revenue	365,127	322,084	356,532
Expense
Interest expense on short and long-term funding	10,942	10,960	16,802
Other expense	7,330	6,422	6,583
Total expense	18,272	17,383	23,384
Income before income tax expense	346,856	304,702	333,148
Income tax expense	(4,138)	(2,070)	6,359
Net income	350,994	306,771	326,790
Preferred stock dividends	17,111	18,358	15,202
Net income available to common equity	$ 333,883	$ 288,413	$ 311,587