Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Securities Available-for-Sale
Amortized Cost	$ 545,433	$ 470,719
Gross Unrealized Gains	1,011	383
Gross Unrealized Losses	(14,606)	(15,036)
Fair Value	531,838	456,066
Securities Held-to-Maturity
Amortized Cost		247,746
Gross Unrealized Gains		4,894
Gross Unrealized Losses		(965)
Fair Value		251,675
Other disclosures
Purchases	210,681	196,082	$ 325,020
Sales	306,400	70,176	$ 296,013
Securities pledged to secure deposits and for other purposes		340,200
U.S. Treasury
Securities Available-for-Sale
Amortized Cost		1,509
Fair Value		1,509
U.S. government agencies
Securities Available-for-Sale
Amortized Cost		1,683
Gross Unrealized Losses		(127)
Fair Value		1,556
States and political subdivisions
Securities Available-for-Sale
Amortized Cost	68,718	30,341
Gross Unrealized Gains	258	285
Gross Unrealized Losses	(273)	(100)
Fair Value	68,703	30,526
Corporate bonds
Securities Available-for-Sale
Amortized Cost	10,957	30,157
Gross Unrealized Gains	9
Gross Unrealized Losses	(336)	(757)
Fair Value	10,630	29,400
Collateralized mortgage obligations
Securities Available-for-Sale
Amortized Cost	174,352	68,743
Gross Unrealized Gains	374	24
Gross Unrealized Losses	(3,799)	(1,847)
Fair Value	170,927	66,920
Securities Held-to-Maturity
Amortized Cost		211,241
Gross Unrealized Gains		3,302
Gross Unrealized Losses		(965)
Fair Value		213,578
Asset-backed securities
Securities Available-for-Sale
Amortized Cost	146,391	241,872
Gross Unrealized Gains	341	74
Gross Unrealized Losses	(8,325)	(10,038)
Fair Value	138,407	231,908
FFEL
Securities Available-for-Sale
Fair Value	117,400
Collateralized loan obligations
Securities Available-for-Sale
Amortized Cost	102,504	94,374
Gross Unrealized Gains	29
Gross Unrealized Losses	(896)	(2,123)
Fair Value	101,637	92,251
U.S. government agency mortgage-backed
Securities Available-for-Sale
Amortized Cost	42,511	2,040
Gross Unrealized Losses	(977)	(44)
Fair Value	41,534	1,996
Securities Held-to-Maturity
Amortized Cost		36,505
Gross Unrealized Gains		1,592
Fair Value		$ 38,097
States and political subdivisions & collateralized loan obligations
Other disclosures
Purchases	92,300
Sales	287,700
Paydown	31,800
Talmer
Other disclosures
Decline in securities	$ 172,000

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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The fair value of available-for-sale securities that serve as collateral for borrowings.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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The cash outflow to acquire debt and equity securities not classified as either held-to-maturity securities or trading securities which would be classified as available-for-sale securities and reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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