Securities - Gross Unrealized Losses and Fair Value by Investment Category (Details) $ in Thousands	Mar. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Available for Sale:
Number of positions, Less than 12 Months | security	134	247
Fair Value, Less than 12 Months	$ 434,112	$ 726,431
Unrealized Losses, Less than 12 Months	$ (11,899)	$ (41,924)
Number of positions, 12 Months or More | security	191	98
Fair value, 12 Months or More	$ 1,036,610	$ 788,657
Unrealized Losses, 12 Months or More	$ (168,914)	$ (159,375)
Number of positions | security	325	345
Fair Value	$ 1,470,722	$ 1,515,088
Unrealized Losses	$ (180,813)	$ (201,299)
Held to Maturity:
Number of positions, Less than 12 Months | security	8	122
Fair Value, Less than 12 Months	$ 125,322	$ 448,575
Unrealized Losses, Less than 12 Months	$ (3,621)	$ (51,436)
Number of positions, 12 Months or More | security	228	115
Fair Value, 12 Months or More	$ 1,074,589	$ 755,527
Unrealized Losses, 12 Months or More	$ (92,663)	$ (66,113)
Number of positions | security	236	237
Fair Value	$ 1,199,911	$ 1,204,102
Unrealized Losses	$ (96,284)	$ (117,549)
Obligations of other U.S. Government agencies and corporations
Available for Sale:
Number of positions, Less than 12 Months | security	5	5
Fair Value, Less than 12 Months	$ 165,890	$ 164,660
Unrealized Losses, Less than 12 Months	$ (4,110)	$ (5,340)
Number of positions, 12 Months or More | security	0	0
Fair value, 12 Months or More	$ 0	$ 0
Unrealized Losses, 12 Months or More	$ 0	$ 0
Number of positions | security	5	5
Fair Value	$ 165,890	$ 164,660
Unrealized Losses	$ (4,110)	$ (5,340)
Obligations of states and political subdivisions
Available for Sale:
Number of positions, Less than 12 Months | security	39	84
Fair Value, Less than 12 Months	$ 38,653	$ 96,939
Unrealized Losses, Less than 12 Months	$ (248)	$ (4,869)
Number of positions, 12 Months or More | security	41	11
Fair value, 12 Months or More	$ 81,072	$ 33,038
Unrealized Losses, 12 Months or More	$ (6,618)	$ (4,499)
Number of positions | security	80	95
Fair Value	$ 119,725	$ 129,977
Unrealized Losses	$ (6,866)	$ (9,368)
Held to Maturity:
Number of positions, Less than 12 Months | security	1	105
Fair Value, Less than 12 Months	$ 440	$ 191,442
Unrealized Losses, Less than 12 Months	$ 0	$ (35,871)
Number of positions, 12 Months or More | security	127	24
Fair Value, 12 Months or More	$ 247,694	$ 49,697
Unrealized Losses, 12 Months or More	$ (38,774)	$ (12,454)
Number of positions | security	128	129
Fair Value	$ 248,134	$ 241,139
Unrealized Losses	$ (38,774)	$ (48,325)
Other debt securities
Available for Sale:
Number of positions, Less than 12 Months | security	15	25
Fair Value, Less than 12 Months	$ 35,768	$ 63,423
Unrealized Losses, Less than 12 Months	$ (1,177)	$ (3,167)
Number of positions, 12 Months or More | security	9	1
Fair value, 12 Months or More	$ 23,608	$ 7,412
Unrealized Losses, 12 Months or More	$ (2,668)	$ (883)
Number of positions | security	24	26
Fair Value	$ 59,376	$ 70,835
Unrealized Losses	$ (3,845)	$ (4,050)
Held to Maturity:
Number of positions, Less than 12 Months | security	1	2
Fair Value, Less than 12 Months	$ 23,156	$ 42,567
Unrealized Losses, Less than 12 Months	$ (625)	$ (2,013)
Number of positions, 12 Months or More | security	9	8
Fair Value, 12 Months or More	$ 34,639	$ 16,042
Unrealized Losses, 12 Months or More	$ (2,647)	$ (2,253)
Number of positions | security	10	10
Fair Value	$ 57,795	$ 58,609
Unrealized Losses	$ (3,272)	$ (4,266)
Government agency mortgage backed securities | Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	63	97
Fair Value, Less than 12 Months	$ 128,869	$ 214,516
Unrealized Losses, Less than 12 Months	$ (4,799)	$ (15,115)
Number of positions, 12 Months or More | security	62	29
Fair value, 12 Months or More	$ 309,322	$ 237,970
Unrealized Losses, 12 Months or More	$ (41,013)	$ (36,921)
Number of positions | security	125	126
Fair Value	$ 438,191	$ 452,486
Unrealized Losses	$ (45,812)	$ (52,036)
Held to Maturity:
Number of positions, Less than 12 Months | security	2	8
Fair Value, Less than 12 Months	$ 42,422	$ 94,258
Unrealized Losses, Less than 12 Months	$ (751)	$ (4,186)
Number of positions, 12 Months or More | security	68	62
Fair Value, 12 Months or More	$ 408,755	$ 364,870
Unrealized Losses, 12 Months or More	$ (18,905)	$ (20,246)
Number of positions | security	70	70
Fair Value	$ 451,177	$ 459,128
Unrealized Losses	$ (19,656)	$ (24,432)
Government agency mortgage backed securities | Commercial mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	1	4
Fair Value, Less than 12 Months	$ 395	$ 10,114
Unrealized Losses, Less than 12 Months	$ (1)	$ (1,053)
Number of positions, 12 Months or More | security	3	0
Fair value, 12 Months or More	$ 9,833	$ 0
Unrealized Losses, 12 Months or More	$ (899)	$ 0
Number of positions | security	4	4
Fair Value	$ 10,228	$ 10,114
Unrealized Losses	$ (900)	$ (1,053)
Held to Maturity:
Number of positions, Less than 12 Months | security	0	1
Fair Value, Less than 12 Months	$ 0	$ 13,745
Unrealized Losses, Less than 12 Months	$ 0	$ (3,261)
Number of positions, 12 Months or More | security	1	0
Fair Value, 12 Months or More	$ 14,069	$ 0
Unrealized Losses, 12 Months or More	$ (2,931)	$ 0
Number of positions | security	1	1
Fair Value	$ 14,069	$ 13,745
Unrealized Losses	$ (2,931)	$ (3,261)
Government agency collateralized mortgage obligations | Residential mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	4	16
Fair Value, Less than 12 Months	$ 30,958	$ 109,753
Unrealized Losses, Less than 12 Months	$ (728)	$ (8,552)
Number of positions, 12 Months or More | security	48	36
Fair value, 12 Months or More	$ 463,558	$ 391,416
Unrealized Losses, 12 Months or More	$ (94,316)	$ (95,312)
Number of positions | security	52	52
Fair Value	$ 494,516	$ 501,169
Unrealized Losses	$ (95,044)	$ (103,864)
Held to Maturity:
Number of positions, Less than 12 Months | security	2	4
Fair Value, Less than 12 Months	$ 51,648	$ 98,912
Unrealized Losses, Less than 12 Months	$ (1,622)	$ (5,479)
Number of positions, 12 Months or More | security	16	14
Fair Value, 12 Months or More	$ 338,265	$ 293,698
Unrealized Losses, 12 Months or More	$ (23,708)	$ (25,227)
Number of positions | security	18	18
Fair Value	$ 389,913	$ 392,610
Unrealized Losses	$ (25,330)	$ (30,706)
Government agency collateralized mortgage obligations | Commercial mortgage backed securities:
Available for Sale:
Number of positions, Less than 12 Months | security	7	16
Fair Value, Less than 12 Months	$ 33,579	$ 67,026
Unrealized Losses, Less than 12 Months	$ (836)	$ (3,828)
Number of positions, 12 Months or More | security	28	21
Fair value, 12 Months or More	$ 149,217	$ 118,821
Unrealized Losses, 12 Months or More	$ (23,400)	$ (21,760)
Number of positions | security	35	37
Fair Value	$ 182,796	$ 185,847
Unrealized Losses	$ (24,236)	$ (25,588)
Held to Maturity:
Number of positions, Less than 12 Months | security	2	2
Fair Value, Less than 12 Months	$ 7,656	$ 7,651
Unrealized Losses, Less than 12 Months	$ (623)	$ (626)
Number of positions, 12 Months or More | security	7	7
Fair Value, 12 Months or More	$ 31,167	$ 31,220
Unrealized Losses, 12 Months or More	$ (5,698)	$ (5,933)
Number of positions | security	9	9
Fair Value	$ 38,823	$ 38,871
Unrealized Losses	$ (6,321)	$ (6,559)