Other Comprehensive Income - Amounts reclassified from accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of investment securities	$ 1,815	$ 1,517	$ 97
Interest income (expense) derivative deposits	(53,566)	(91,026)	(60,210)
Income tax (expense) benefit	(43,928)	(53,848)	(51,932)
Amounts reclassified from accumulated other comprehensive income (loss)	(132,217)	(142,943)	(152,276)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of investment securities	1,815	1,517	97
Interest income (expense) derivative deposits	(1,145)	1,198	560
Income tax (expense) benefit	(167)	(744)	(167)
Amounts reclassified from accumulated other comprehensive income (loss)	$ 503	$ 1,971	$ 490