Accumulated Other Comprehensive Loss Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gains on sale of investment securities									$ (69)	$ 0	$ (4,476)
Actual gain (loss) on plan assets									(880)	434
Income tax expense	$ 6,319	$ 6,193	$ 5,813	$ 5,810	$ 2,646	$ 5,606	$ 5,358	$ 4,405	24,135	18,015	36,435
Net Income Available to Common Shareholders	$ (22,611)	$ (22,371)	$ (22,751)	$ (21,619)	$ (10,713)	$ (20,692)	$ (20,979)	$ (17,616)	(89,352)	(70,002)	(54,310)
Unrealized Gains (Losses) on Securities Available-for-Sale | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gains on sale of investment securities									(69)	0	(4,476)
Income tax expense									15	0	1,657
Net Income Available to Common Shareholders									(54)	0	(2,819)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actual gain (loss) on plan assets									0	163	0
Income tax expense									0	(38)	0
Net Income Available to Common Shareholders									$ 0	$ 125	$ 0