Fair Value (Fair value measurement recurring) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets
Securities available for sale	$ 1,893,528	$ 1,845,864
U.S. government corporations and agencies
Assets
Securities available for sale	15,067	4,700
Mortgage-backed securities
Assets
Securities available for sale	1,288,527	1,290,500
Obligations of states and political subdivisions
Assets
Securities available for sale	574,593	536,144
Equity securities
Assets
Securities available for sale	15,341	14,520
Level 1
Assets
Securities available for sale	10,496	517
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Level 1 \| Interest rate lock commitments
Assets
Derivative assets	0	0
Level 1 \| Forward commitments
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Level 2
Assets
Securities available for sale	1,883,032	1,843,123
Derivative assets	3,278	3,222
Liabilities
Derivative liabilities	6,237	7,027
Level 2 \| Interest rate lock commitments
Assets
Derivative assets	0	0
Level 2 \| Forward commitments
Assets
Derivative assets	176	2,546
Liabilities
Derivative liabilities	634	266
Level 3
Assets
Securities available for sale	0	2,224
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Level 3 \| Interest rate lock commitments
Assets
Derivative assets	3,745	2,790
Level 3 \| Forward commitments
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis
Assets
Total assets at fair value	1,900,727	1,854,422
Liabilities
Total liabilities at fair value	6,871	7,293
Recurring Basis \| Derivative financial instruments
Assets
Derivative assets	3,278	3,222
Liabilities
Derivative liabilities	6,237	7,027
Recurring Basis \| Interest rate lock commitments
Assets
Derivative assets	3,745	2,790
Recurring Basis \| Forward commitments
Assets
Derivative assets	176	2,546
Liabilities
Derivative liabilities	634	266
Recurring Basis \| U.S. government corporations and agencies
Assets
Securities available for sale	15,067	4,700
Recurring Basis \| Mortgage-backed securities
Assets
Securities available for sale	1,288,527	1,290,500
Recurring Basis \| Obligations of states and political subdivisions
Assets
Securities available for sale	574,593	536,144
Recurring Basis \| Equity securities
Assets
Securities available for sale	15,341	14,520
Recurring Basis \| Level 1
Assets
Total assets at fair value	10,496	517
Liabilities
Total liabilities at fair value	0	0
Recurring Basis \| Level 1 \| Derivative financial instruments
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| Level 1 \| Interest rate lock commitments
Assets
Derivative assets	0	0
Recurring Basis \| Level 1 \| Forward commitments
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| Level 1 \| U.S. government corporations and agencies
Assets
Securities available for sale	10,496	517
Recurring Basis \| Level 1 \| Mortgage-backed securities
Assets
Securities available for sale	0	0
Recurring Basis \| Level 1 \| Obligations of states and political subdivisions
Assets
Securities available for sale	0	0
Recurring Basis \| Level 1 \| Equity securities
Assets
Securities available for sale	0	0
Recurring Basis \| Level 2
Assets
Total assets at fair value	1,886,486	1,848,891
Liabilities
Total liabilities at fair value	6,871	7,293
Recurring Basis \| Level 2 \| Derivative financial instruments
Assets
Derivative assets	3,278	3,222
Liabilities
Derivative liabilities	6,237	7,027
Recurring Basis \| Level 2 \| Interest rate lock commitments
Assets
Derivative assets	0	0
Recurring Basis \| Level 2 \| Forward commitments
Assets
Derivative assets	176	2,546
Liabilities
Derivative liabilities	634	266
Recurring Basis \| Level 2 \| U.S. government corporations and agencies
Assets
Securities available for sale	4,571	4,183
Recurring Basis \| Level 2 \| Mortgage-backed securities
Assets
Securities available for sale	1,288,527	1,288,276
Recurring Basis \| Level 2 \| Obligations of states and political subdivisions
Assets
Securities available for sale	574,593	536,144
Recurring Basis \| Level 2 \| Equity securities
Assets
Securities available for sale	15,341	14,520
Recurring Basis \| Level 3
Assets
Total assets at fair value	3,745	5,014
Liabilities
Total liabilities at fair value	0	0
Recurring Basis \| Level 3 \| Derivative financial instruments
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| Level 3 \| Interest rate lock commitments
Assets
Derivative assets	3,745	2,790
Recurring Basis \| Level 3 \| Forward commitments
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Recurring Basis \| Level 3 \| U.S. government corporations and agencies
Assets
Securities available for sale	0	0
Recurring Basis \| Level 3 \| Mortgage-backed securities
Assets
Securities available for sale	0	2,224
Recurring Basis \| Level 3 \| Obligations of states and political subdivisions
Assets
Securities available for sale	0	0
Recurring Basis \| Level 3 \| Equity securities
Assets
Securities available for sale	$ 0	$ 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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