Securities (Details Textual) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities, gross realized gain (loss)	$ 0	$ 0	$ (458,000)	$ 0
Continuous unrealized loss position, fair value	$ 272,100,000		$ 272,100,000			$ 469,800,000
Continuous unrealized loss position, fair value (as a percent)			46.00%		93.00%