Fair Value Accounting (Fair Value Inputs, Assets, Quantitative Information) (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Measurements, Recurring Basis | Visa Derivative | Discounted cash flow analysis | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated future monthly fees payable to the derivative counterparty, period	1 year	1 year
Fair Value, Measurements, Recurring Basis | Visa Derivative | Discounted cash flow analysis | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated future monthly fees payable to the derivative counterparty, period	4 years	4 years
Fair Value, Measurements, Recurring Basis | Earnout Liabilities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure, Nonrecurring	$ 11,348	$ 11,348
Fair Value, Measurements, Recurring Basis | Visa derivative
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure, Nonrecurring	3,974	4,330
Fair Value, Measurements, Recurring Basis | Trust preferred securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 1,852	$ 1,935
Fair Value, Measurements, Recurring Basis | Trust preferred securities | Discounted cash flow analysis
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spread embedded in discount rate	4.39%	3.98%
Fair Value, Measurements, Recurring Basis | Private equity investments | Individual Analysis of Each Investee Company [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 12,715	$ 15,771
Fair Value, Measurements, Recurring Basis | GGL / SBA Loans Servicing Asset
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 3,971	$ 4,101
Fair Value, Measurements, Recurring Basis | GGL / SBA Loans Servicing Asset | Discounted cash flow analysis
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	13.57%	13.16%
Prepayment speeds	7.98%	7.50%
Fair Value, Measurements, Nonrecurring Basis | Collateral dependent impaired loans | Third-party appraised value of collateral less estimated selling costs | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	0.00%	0.00%
Estimated selling costs	0.00%	0.00%
Fair Value, Measurements, Nonrecurring Basis | Collateral dependent impaired loans | Third-party appraised value of collateral less estimated selling costs | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	23.00%	50.00%
Estimated selling costs	10.00%	10.00%
Fair Value, Measurements, Nonrecurring Basis | Collateral dependent impaired loans | Third-party appraised value of collateral less estimated selling costs | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	9.00%	15.00%
Estimated selling costs	7.00%	7.00%
Fair Value, Measurements, Nonrecurring Basis | Other loans held for sale | Third-party appraised value of collateral less estimated selling costs | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	0.00%	5.00%
Estimated selling costs	0.00%	0.00%
Fair Value, Measurements, Nonrecurring Basis | Other loans held for sale | Third-party appraised value of collateral less estimated selling costs | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	85.00%	99.00%
Estimated selling costs	10.00%	10.00%
Fair Value, Measurements, Nonrecurring Basis | Other loans held for sale | Third-party appraised value of collateral less estimated selling costs | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	30.00%	54.00%
Estimated selling costs	2.00%	2.00%
Fair Value, Measurements, Nonrecurring Basis | Other real estate | Third-party appraised value of collateral less estimated selling costs | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	0.00%	0.00%
Estimated selling costs	0.00%	0.00%
Fair Value, Measurements, Nonrecurring Basis | Other real estate | Third-party appraised value of collateral less estimated selling costs | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	39.00%	85.00%
Estimated selling costs	10.00%	10.00%
Fair Value, Measurements, Nonrecurring Basis | Other real estate | Third-party appraised value of collateral less estimated selling costs | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value	21.00%	35.00%
Estimated selling costs	7.00%	7.00%
Fair Value, Measurements, Nonrecurring Basis | Other assets held for sale | Third-party appraised value less estimated selling costs or BOV | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value		21.00%
Estimated selling costs	0.00%	0.00%
Fair Value, Measurements, Nonrecurring Basis | Other assets held for sale | Third-party appraised value less estimated selling costs or BOV | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value		52.00%
Estimated selling costs	10.00%	10.00%
Fair Value, Measurements, Nonrecurring Basis | Other assets held for sale | Third-party appraised value less estimated selling costs or BOV | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount to appraised value		25.00%
Estimated selling costs	7.00%	7.00%