Statements of Cash Flows (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Statement of cash flows specific transaction amounts [Abstract]
Income taxes paid		$ 1,125	$ 18,756
Interest expense paid on deposits and borrowings		16,593	11,590
Noncash transfers from loans to other real estate	[1]	4,023	$ 8,668
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

[1] Includes transfers from covered loans to covered other real estate.