- Income Taxes - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income tax expense, Tax Cuts And Jobs Act Of 2017, deferred tax assets and liabilities	$ 11,700
Deferred income tax expense (benefit), unrealized gains (losses)		$ (119)	$ 1,400	$ 6,400	$ (2,600)
Other comprehensive income (loss), defined benefit plan, gain (loss), reclassification adjustment from AOCI, tax		(94)	(530)	$ (4,213)	$ (3,259)
Included in retained earnings, no provision for income tax	21,500	21,500	21,500
Valuation allowance	2,786	2,786	2,388
State NOL	$ 2,476	$ 2,476	$ 2,063