Accumulated Other Comprehensive Loss Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gains on sale of investment securities									$ 0	$ (4,476)	$ (3,513)
Actual gain (loss) on plan assets									(434)	1,890
Income tax expense	$ 2,646	$ 5,606	$ 5,358	$ 4,405	$ 14,972	$ 7,003	$ 6,812	$ 7,647	18,015	36,435	25,083
Net Income Available to Common Shareholders	$ (10,713)	$ (20,692)	$ (20,979)	$ (17,616)	$ (9,669)	$ (13,932)	$ (14,685)	$ (16,026)	(70,002)	(54,310)	(52,128)
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									0	(4,476)	(3,513)
Income tax expense									0	1,657	1,297
Net Income Available to Common Shareholders									0	$ (2,819)	$ (2,216)
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									(163)
Income tax expense									(38)
Net Income Available to Common Shareholders									$ 125