Derivatives (Details) - Interest Rate Swap - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Fair Value Hedging
Summarized details of swaps outstanding and the related hedged items
Aggregate notional amount	$ 725,000,000
Derivative, fair value	10,000,000	$ 7,000,000
Cash Flow Hedging
Summarized details of swaps outstanding and the related hedged items
Aggregate notional amount	$ 15,492,000