Securities - Investments in Pooled Trust Preferred Securities (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Investments in pooled trust preferred securities
Amortized Cost	$ 1,201,389	$ 674,104
Fair Value	1,177,606	671,488
Unrealized Loss	(26,983)	(10,488)
Trust preferred securities
Investments in pooled trust preferred securities
Amortized Cost	12,351	12,442
Fair Value	10,304	$ 9,388
Unrealized Loss	(2,047)
XXIII
Investments in pooled trust preferred securities
Amortized Cost	8,283
Fair Value	6,689
Unrealized Loss	$ (1,594)
Issuers Currently in Deferral or Default	16.00%
XXVI
Investments in pooled trust preferred securities
Amortized Cost	$ 4,068
Fair Value	3,615
Unrealized Loss	$ (453)
Issuers Currently in Deferral or Default	19.00%

Percentage of issuers currently in deferral or default.

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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