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Fair Value Measurement and Fair Value of Financial Instruments (Quantitative Information for Significant Unobservable Inputs) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Non-PCI Loans | Fair Value, Measurements, Nonrecurring
Quantitative information
Non-PCI impaired loans	$ 37,174	$ 38,188
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Quantitative information
Non-PCI impaired loans	37,174	38,188
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Discounted cash flows | Fair Value, Measurements, Nonrecurring
Quantitative information
Non-PCI impaired loans	$ 28,596	$ 22,802
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Discounted cash flows | Fair Value, Measurements, Nonrecurring | Weighted Average
Quantitative information
Discount	5.00%	6.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Discounted cash flows | Fair Value, Measurements, Nonrecurring | Minimum
Quantitative information
Discount	4.00%	4.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Discounted cash flows | Fair Value, Measurements, Nonrecurring | Maximum
Quantitative information
Discount	7.00%	10.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair value of property | Fair Value, Measurements, Nonrecurring
Quantitative information
Non-PCI impaired loans	$ 3,114	$ 9,773
Selling cost	8.00%	8.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair value of property | Fair Value, Measurements, Nonrecurring | Weighted Average
Quantitative information
Selling cost	8.00%	8.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair value of collateral, discount | Fair Value, Measurements, Nonrecurring
Quantitative information
Non-PCI impaired loans	$ 4,849	$ 3,207
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair value of collateral, discount | Fair Value, Measurements, Nonrecurring | Weighted Average
Quantitative information
Discount	39.00%	29.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair value of collateral, discount | Fair Value, Measurements, Nonrecurring | Minimum
Quantitative information
Discount	15.00%	20.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair value of collateral, discount | Fair Value, Measurements, Nonrecurring | Maximum
Quantitative information
Discount	50.00%	32.00%
Non-PCI Loans | Significant Unobservable Inputs (Level 3) | Fair value of collateral, contract value | Fair Value, Measurements, Nonrecurring
Quantitative information
Non-PCI impaired loans	$ 615	$ 2,406
OREO | Fair Value, Measurements, Nonrecurring
Quantitative information
OREO		9
OREO | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring
Quantitative information
OREO		9
OREO | Significant Unobservable Inputs (Level 3) | Fair value of property | Fair Value, Measurements, Nonrecurring
Quantitative information
OREO		$ 9
Selling cost		8.00%
OREO | Significant Unobservable Inputs (Level 3) | Fair value of property | Fair Value, Measurements, Nonrecurring | Weighted Average
Quantitative information
Selling cost		8.00%
Equity warrants | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Quantitative information
Equity warrants	$ 931	$ 679
Equity warrants | Significant Unobservable Inputs (Level 3) | Black-Scholes option pricing model | Fair Value, Measurements, Recurring | Weighted Average
Quantitative information
Volatility	48.00%
Liquidity discount	47.00%

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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