Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Statement of cash flows specific transaction amounts [Abstract]
Income taxes paid	$ 4,620	$ 1,125
Interest expense paid on deposits and borrowings	29,045	16,593
Noncash transfers from loans to other real estate	$ 7,084	4,023
Transfer of long-term FHLB advances to short-term		250,038
Assets acquired in business combination		196,265
Liabilities acquired in business combination		$ 184,949