Derivatives, Hedging Activities, and Other Financial Instruments - Notional and Fair Value of Derivatives Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Other assets
Derivative [Line Items]
Credit risk derivative asset, fair value	$ 14,477	$ 1,722
Other liabilities
Derivative [Line Items]
Credit risk derivative liability, fair value	$ 15,170	$ 1,813