Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	$ 16,061	$ 19,197
Loans with a specific valuation allowance, Unpaid principal balance	16,061	19,491
Specific valuation allowance	702	3,223
Loans with a specific valuation allowance, Average balance	17,629	19,519
Loans without a specific valuation allowance, Recorded balance	88,350	89,591
Loans without a specific valuation allowance, Unpaid principal balance	105,100	107,486
Loans without a specific valuation allowance, Average balance	88,970	106,747
Recorded balance	104,411	108,788
Unpaid principal balance	121,161	126,977
Average balance	106,599	126,266
Residential Real Estate | Residential Real Estate
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	44	1,957
Loans with a specific valuation allowance, Unpaid principal balance	44	2,220
Specific valuation allowance	1	83
Loans with a specific valuation allowance, Average balance	1,001	2,686
Loans without a specific valuation allowance, Recorded balance	10,602	10,728
Loans without a specific valuation allowance, Unpaid principal balance	12,009	11,989
Loans without a specific valuation allowance, Average balance	10,665	10,269
Recorded balance	10,646	12,685
Unpaid principal balance	12,053	14,209
Average balance	11,666	12,955
Commercial | Commercial Real Estate
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	6,004	9,345
Loans with a specific valuation allowance, Unpaid principal balance	6,004	9,345
Specific valuation allowance	57	568
Loans with a specific valuation allowance, Average balance	7,674	8,498
Loans without a specific valuation allowance, Recorded balance	59,100	59,492
Loans without a specific valuation allowance, Unpaid principal balance	69,991	71,300
Loans without a specific valuation allowance, Average balance	59,296	73,889
Recorded balance	65,104	68,837
Unpaid principal balance	75,995	80,645
Average balance	66,970	82,387
Commercial | Other Commercial
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	10,004	7,268
Loans with a specific valuation allowance, Unpaid principal balance	10,004	7,268
Specific valuation allowance	642	2,313
Loans with a specific valuation allowance, Average balance	8,636	7,081
Loans without a specific valuation allowance, Recorded balance	12,950	13,707
Loans without a specific valuation allowance, Unpaid principal balance	16,516	17,689
Loans without a specific valuation allowance, Average balance	13,328	17,376
Recorded balance	22,954	20,975
Unpaid principal balance	26,520	24,957
Average balance	21,964	24,457
Consumer and Other | Home Equity
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	0	120
Loans with a specific valuation allowance, Unpaid principal balance	0	120
Specific valuation allowance	0	39
Loans with a specific valuation allowance, Average balance	60	82
Loans without a specific valuation allowance, Recorded balance	3,057	3,377
Loans without a specific valuation allowance, Unpaid principal balance	3,699	3,986
Loans without a specific valuation allowance, Average balance	3,217	3,465
Recorded balance	3,057	3,497
Unpaid principal balance	3,699	4,106
Average balance	3,277	3,547
Consumer and Other | Other Consumer
Summary of the impaired loans by portfolio class of loans
Loans with a specific valuation allowance, Recorded balance	9	507
Loans with a specific valuation allowance, Unpaid principal balance	9	538
Specific valuation allowance	2	220
Loans with a specific valuation allowance, Average balance	258	1,172
Loans without a specific valuation allowance, Recorded balance	2,641	2,287
Loans without a specific valuation allowance, Unpaid principal balance	2,885	2,522
Loans without a specific valuation allowance, Average balance	2,464	1,748
Recorded balance	2,650	2,794
Unpaid principal balance	2,894	3,060
Average balance	$ 2,722	$ 2,920