Net income per common share - Computation of net income (loss) per common share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share
Net income	$ 158,979	$ 211,686
Preferred stock dividends	(353)	(353)
Net income applicable to common stock	$ 158,626	$ 211,333
Average common shares outstanding	71,541,778	78,443,706
Average potential dilutive common shares	64,418	151,757
Average common shares outstanding - assuming dilution	71,606,196	78,595,463
Basic EPS	$ 2.22	$ 2.69
Diluted EPS	$ 2.22	$ 2.69