Acquisitions (Acquisitions fair values) (Details) - USD ($) $ in Thousands	Jul. 07, 2017	Sep. 30, 2017	Dec. 31, 2016
Fair value of liabilities assumed
Goodwill resulting from acquisition		$ 236,615	$ 127,699
Citywide Banks
Fair value of consideration paid
Common stock	$ 152,607
Common stock (in shares)	3,216,161
Cash	$ 58,636
Total consideration paid	211,243
Fair value of assets acquired
Cash and due from banks	21,341
Interest bearing deposits in other financial institutions	74,686
Time deposits in other financial institutions	6,304
Securities
Securities available for sale	234,390
Other securities	2,628
Loans held to maturity	985,399
Premises, furniture and equipment, net	17,206
Premises, furniture and equipment held for sale	1,350
Other real estate, net	6,916
Other intangible assets, net	16,041
Other assets	32,278
Total assets	1,398,539
Fair value of liabilities assumed
Deposits	1,210,074
Short term borrowings	34,445
Other borrowings	21,636
Other liabilities	16,295
Total liabilities assumed	1,282,450
Fair value of net assets acquired	116,089
Goodwill resulting from acquisition	$ 95,154