CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 166,299	$ 235,107	$ 96,953
Investments available-for-sale:
Net change in unrealized gains/ (losses) on investments available-for-sale	(152,196)	(38,104)	32,950
Related income tax (expense)/ benefit	38,762	9,751	(8,428)
Net investment (gains)/ losses reclassified into earnings	345	(212)	(467)
Related income tax expense/ (benefit)	(88)	54	120
Net effect on other comprehensive income/ (loss)	(113,177)	(28,511)	24,175
Investments held-to-maturity:
Net change in unrealized loss	(14,003)	0	0
Related income tax benefit	3,567	0	0
Net effect on other comprehensive income/ (loss)	(10,436)	0	0
Defined benefit pension plan:
Net change in unrealized gains/ (losses)	294	1,687	(1,542)
Related income tax (expense)/ benefit	(93)	(420)	404
Net effect on other comprehensive income/ (loss)	201	1,267	(1,138)
Total other comprehensive income/ (loss)	(123,412)	(27,244)	23,037
Comprehensive income	$ 42,887	$ 207,863	$ 119,990