Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Cash dividends paid to parent Company by consolidated subsidiaries	$ 59.0	$ 22.2	$ 77.0
Amount available to be paid as dividends without prior regulatory approval	$ 156.9
Minimum ratio of qualifying total capital to risk-weighted assets	8.00%
Common Equity Tier 1 capital required for capital adequacy to risk weighted assets	4.50%
Tier 1 risk based capital required for capital adequacy to risk weighted assets	6.00%
Tier 1 leverage capital required for capital adequacy to average assets	4.00%
Ratios required for the banks to be well capitalized, Total Capital to Risk-Weighted Assets	10.00%
Ratios required for the banks to be well capitalized, Tier1 Capital to Risk-Weighted Assets	8.00%
Ratio required for the banks to be well capitalized, Common Equity Tier 1 Capital to Risk-Weighted Assets	6.50%
Ratios required for the banks to be well capitalized, Tier 1 Leverage Ratio	5.00%
Federal Reserve Bank
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Cash reserve requirement	$ 507.0	$ 412.7