Borrowings and Subordinated Debentures (Details) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) item	Jun. 30, 2017 item	Mar. 31, 2017 USD ($)
Advances from the Federal Home Loan Bank [Abstract]
Line of credit with federal home loan bank, amount	$ 326,000
Federal Home Loan Bank, advances, activity for year, average balance of agreements outstanding	40,000		$ 69,000
Federal Home Loan Bank, advances, general debt obligations, disclosures, collateral pledged	8,600
Amount [Abstract]
2017	15,000		44,000
2018	10,000		10,000
2019	15,000		15,000
Total FHLB borrowings	$ 40,000		$ 69,000
Rate [Abstract]
2017	1.33%		1.19%
2018	2.01%		2.01%
2019	1.40%		1.40%
Repayments of Long-term Debt	$ 25,000	$ 11,970
Line of credit maximum borrowing capacity	$ 20,000
Number of financial institutions | item			2	2
Outstanding line of credit			$ 0		$ 0
Notes payable | Notes PayableTo PNCBank Due January2018 Member
Rate [Abstract]
Notes payable with PNC Bank			$ 35,000		$ 35,000
Weighted average interest rate on other borrowings from PNC Bank (as a percent)	3.65%