Fair Value (Fair value measurement recurring) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Securities available for sale	$ 2,274,215	$ 2,216,753
Equity securities with a readily determinable fair value	16,916
Securities available for sale		2,216,753
Level 1
Assets
Securities available for sale	25,367	3,484
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Level 2
Assets
Securities available for sale	2,248,848	2,213,269
Derivative assets	9,126	3,933
Liabilities
Derivative liabilities	5,940	5,167
Level 3
Assets
Securities available for sale	0	0
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Interest rate lock commitments \| Level 1
Assets
Derivative assets	0	0
Interest rate lock commitments \| Level 2
Assets
Derivative assets	0	0
Interest rate lock commitments \| Level 3
Assets
Derivative assets	1,539	1,738
Forward commitments \| Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Forward commitments \| Level 2
Assets
Derivative assets	353	80
Liabilities
Derivative liabilities	69	232
Forward commitments \| Level 3
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
U.S. government corporations and agencies
Assets
Securities available for sale	26,997
Securities available for sale		5,328
Mortgage and asset-backed securities
Assets
Securities available for sale	1,871,819
Securities available for sale		1,753,736
Obligations of states and political subdivisions
Assets
Securities available for sale	358,483
Securities available for sale		441,015
Equity securities with a readily determinable fair value
Assets
Securities available for sale		16,674
Recurring Basis
Assets
Equity securities with a readily determinable fair value	16,916
Total assets at fair value	2,285,434	2,222,504
Liabilities
Total liabilities at fair value	6,009	5,399
Recurring Basis \| Level 1
Assets
Equity securities with a readily determinable fair value	0
Total assets at fair value	25,367	3,484
Liabilities
Total liabilities at fair value	0	0
Recurring Basis \| Level 2
Assets
Equity securities with a readily determinable fair value	16,916
Total assets at fair value	2,258,528	2,217,282
Liabilities
Total liabilities at fair value	6,009	5,399
Recurring Basis \| Level 3
Assets
Equity securities with a readily determinable fair value	0
Total assets at fair value	1,539	1,738
Liabilities
Total liabilities at fair value	0	0
Recurring Basis \| Derivative Financial Instruments
Assets
Derivative assets	9,327	3,933
Liabilities
Derivative liabilities	5,940	5,167
Recurring Basis \| Derivative Financial Instruments \| Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| Derivative Financial Instruments \| Level 2
Assets
Derivative assets	9,327	3,933
Liabilities
Derivative liabilities	5,940	5,167
Recurring Basis \| Derivative Financial Instruments \| Level 3
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| Interest rate lock commitments
Assets
Derivative assets	1,539	1,738
Recurring Basis \| Interest rate lock commitments \| Level 1
Assets
Derivative assets	0	0
Recurring Basis \| Interest rate lock commitments \| Level 2
Assets
Derivative assets	0	0
Recurring Basis \| Interest rate lock commitments \| Level 3
Assets
Derivative assets	1,539	1,738
Recurring Basis \| Forward commitments
Assets
Derivative assets	353	80
Liabilities
Derivative liabilities	69	232
Recurring Basis \| Forward commitments \| Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| Forward commitments \| Level 2
Assets
Derivative assets	353	80
Liabilities
Derivative liabilities	69	232
Recurring Basis \| Forward commitments \| Level 3
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| U.S. government corporations and agencies
Assets
Securities available for sale	26,997
Securities available for sale		5,328
Recurring Basis \| U.S. government corporations and agencies \| Level 1
Assets
Securities available for sale	25,367
Securities available for sale		3,484
Recurring Basis \| U.S. government corporations and agencies \| Level 2
Assets
Securities available for sale	1,630
Securities available for sale		1,844
Recurring Basis \| U.S. government corporations and agencies \| Level 3
Assets
Securities available for sale	0
Securities available for sale		0
Recurring Basis \| Mortgage and asset-backed securities
Assets
Securities available for sale	1,871,819
Securities available for sale		1,753,736
Recurring Basis \| Mortgage and asset-backed securities \| Level 1
Assets
Securities available for sale	0
Securities available for sale		0
Recurring Basis \| Mortgage and asset-backed securities \| Level 2
Assets
Securities available for sale	1,871,819
Securities available for sale		1,753,736
Recurring Basis \| Mortgage and asset-backed securities \| Level 3
Assets
Securities available for sale	0
Securities available for sale		0
Recurring Basis \| Obligations of states and political subdivisions
Assets
Securities available for sale	358,483
Securities available for sale		441,015
Recurring Basis \| Obligations of states and political subdivisions \| Level 1
Assets
Securities available for sale	0
Securities available for sale		0
Recurring Basis \| Obligations of states and political subdivisions \| Level 2
Assets
Securities available for sale	358,483
Securities available for sale		441,015
Recurring Basis \| Obligations of states and political subdivisions \| Level 3
Assets
Securities available for sale	$ 0
Securities available for sale		0
Recurring Basis \| Equity securities with a readily determinable fair value
Assets
Securities available for sale		16,674
Recurring Basis \| Equity securities with a readily determinable fair value \| Level 1
Assets
Securities available for sale		0
Recurring Basis \| Equity securities with a readily determinable fair value \| Level 2
Assets
Securities available for sale		16,674
Recurring Basis \| Equity securities with a readily determinable fair value \| Level 3
Assets
Securities available for sale		$ 0

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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