v3.26.3
Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2026
Jun. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Accumulated other comprehensive income (loss), before tax                
Investment securities, OCI (loss) $ (36,183)     $ 7,727     $ (50,667) $ 22,967
Pension and other postretirement plans, OCI (loss) 390     (1,336)     1,171 (2,278)
OCI (loss) (35,793)     6,391     (49,496) 20,689
Accumulated other comprehensive income (loss), tax                
Investment securities, OCI (loss) (7,599)     1,622     (10,640) 4,823
Pension and other postretirement plans, OCI (loss) 82     (280)     246 (478)
OCI (loss) (7,517)     1,342     (10,394) 4,345
Accumulated other comprehensive income (loss), net of tax                
Net of tax, beginning balance 2,467,106 $ 2,353,521 $ 2,283,374 2,184,545 $ 2,067,351 $ 1,987,258 2,283,374 1,987,258
Investment securities, OCI (loss) (28,584)     6,105     (40,027) 18,144
Pension and other postretirement plans, OCI (loss) 308     (1,056)     925 (1,800)
OCI (loss) (28,276) 1,400 (12,226) 5,049 6,078 5,217 (39,102) 16,344
Net of tax, ending balance 2,552,710 2,467,106 2,353,521 2,308,878 2,184,545 2,067,351 2,552,710 2,308,878
Total                
Accumulated other comprehensive income (loss), before tax                
Before tax, beginning balance (79,554)   (65,851) (45,946)   (60,244) (65,851) (60,244)
Before tax, ending balance (115,347) (79,554)   (39,555) (45,946)   (115,347) (39,555)
Accumulated other comprehensive income (loss), tax                
Income Tax, beginning balance (16,707)   (13,830) (9,650)   (12,653) (13,830) (12,653)
Income Tax, ending balance (24,224) (16,707)   (8,308) (9,650)   (24,224) (8,308)
Accumulated other comprehensive income (loss), net of tax                
Net of tax, beginning balance (62,847) (64,247) (52,021) (36,296) (42,374) (47,591) (52,021) (47,591)
OCI (loss) (28,276) 1,400 (12,226) 5,049 6,078 5,217    
Net of tax, ending balance (91,123) (62,847) (64,247) (31,247) (36,296) (42,374) (91,123) (31,247)
Investment securities:                
Accumulated other comprehensive income (loss), before tax                
Before tax, beginning balance (12,976)   1,508 (7,202)   (22,442) 1,508 (22,442)
OCI (loss) before reclassifications (36,903)     7,803     (52,814) 21,264
Realized investment losses (gains) 712     (571)     1,526 122
Impairment losses 8     495     621 1,581
Investment securities, OCI (loss) (36,183)     7,727     (50,667) 22,967
Before tax, ending balance (49,159) (12,976)   525 (7,202)   (49,159) 525
Accumulated other comprehensive income (loss), tax                
Income Tax, beginning balance (2,725)   316 (1,513)   (4,714) 316 (4,714)
OCI (loss) before reclassifications (7,749)     1,638     (11,090) 4,465
Realized investment losses 149     (120)     320 26
Impairment losses 1     104     130 332
Investment securities, OCI (loss) (7,599)     1,622     (10,640) 4,823
Income Tax, ending balance (10,324) (2,725)   109 (1,513)   (10,324) 109
Accumulated other comprehensive income (loss), net of tax                
Net of tax, beginning balance (10,251)   1,192 (5,689)   (17,728) 1,192 (17,728)
OCI (loss) before reclassifications (29,154)     6,165     (41,724) 16,799
Realized investment losses 563     (451)     1,206 96
Impairment losses 7     391     491 1,249
Net of tax, ending balance (38,835) (10,251)   416 (5,689)   (38,835) 416
Pension and other postretirement plans:                
Accumulated other comprehensive income (loss), before tax                
Before tax, beginning balance (66,578)   (67,359) (38,744)   (37,802) (67,359) (37,802)
OCI (loss) before reclassifications 0     (1,063)     0 (1,063)
Amortization of prior service costs 458     422     1,374 1,266
Amortization of net actuarial gain (68)     (633)     (203) (1,942)
Settlement gain 0     (62)     0 (539)
Pension and other postretirement plans, OCI (loss) 390     (1,336)     1,171 (2,278)
Before tax, ending balance (66,188) (66,578)   (40,080) (38,744)   (66,188) (40,080)
Accumulated other comprehensive income (loss), tax                
Income Tax, beginning balance (13,982)   (14,146) (8,137)   (7,939) (14,146) (7,939)
OCI (loss) before reclassifications 0     (223)     0 (223)
Amortization of prior service costs 97     89     289 266
Amortization of net actuarial gain (15)     (133)     (43) (408)
Settlement gain 0     (13)     0 (113)
Pension and other postretirement plans, OCI (loss) 82     (280)     246 (478)
Income Tax, ending balance (13,900) (13,982)   (8,417) (8,137)   (13,900) (8,417)
Accumulated other comprehensive income (loss), net of tax                
Net of tax, beginning balance (52,596)   $ (53,213) (30,607)   $ (29,863) (53,213) (29,863)
OCI (loss) before reclassifications 0     (840)     0 (840)
Amortization of prior service costs 361     333     1,085 1,000
Amortization of net actuarial gain (53)     (500)     (160) (1,534)
Settlement gain 0     (49)     0 (426)
Pension and other postretirement plans, OCI (loss) 308     (1,056)     925 (1,800)
Net of tax, ending balance $ (52,288) $ (52,596)   $ (31,663) $ (30,607)   $ (52,288) $ (31,663)