Securities (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) Investment	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Investment	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Held to maturity securities, transferred from available for sale				$ 0
Investment security losses, net	$ (300,000)	$ 0	$ (500,000)	(200,000)
Gross proceeds from sale of securities	$ 101,800,000	176,600,000	229,300,000	178,600,000
Sale of investment securities realized gain			100,000	1,500,000
Sale of investment securities realized loss			$ 400,000	1,500,000
Number of securities in an unrealized loss position | Investment	1,120		1,120
Total fair value	$ 24,700,000,000		$ 24,700,000,000
Total unrealized losses	170,200,000		170,200,000
Debt securities, unrealized losses	170,200,000		170,200,000		$ 357,100,000
OTTI losses	200,000	$ 0	200,000	200,000
CRA Eligible, Mortgage Backed Securities
Debt and Equity Securities, FV-NI [Line Items]
Investment security losses, net	200,000		200,000
OTTI losses	200,000		200,000	$ 200,000
Government Sponsored Agency
Debt and Equity Securities, FV-NI [Line Items]
Total unrealized losses	63,700,000		63,700,000
Debt securities, unrealized losses	63,700,000		63,700,000		150,500,000
Corporate Debt
Debt and Equity Securities, FV-NI [Line Items]
Total unrealized losses	6,300,000		6,300,000
Debt securities, unrealized losses	$ 6,300,000		$ 6,300,000		22,900,000
Percent of corporate debt portfolio	30.00%		30.00%
Other
Debt and Equity Securities, FV-NI [Line Items]
Total unrealized losses	$ 72,200,000		$ 72,200,000
Debt securities, unrealized losses	$ 72,200,000		$ 72,200,000		$ 69,600,000