Other Comprehensive Income - Amounts reclassified from accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of investment securities	$ 318	$ 713	$ 539	$ 1,535
Interest income derivative deposits	(6,799)	(12,514)	(14,698)	(33,060)
Income tax expense	(16,687)	(9,433)	(31,261)	(17,755)
Net Income	47,993	28,856	91,462	51,979
Reclassification out of Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of investment securities	318	713	539	1,535
Interest income derivative deposits	(133)	(393)	(517)	(299)
Income tax expense	(48)	(78)	(5)	(314)
Net Income	$ 137	$ 242	$ 17	$ 922