Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of cash flows specific transaction amounts [Abstract]
Income taxes paid		$ 12,435	$ 7,371	$ 24,836
Interest paid on deposits and borrowings		66,358	41,472	24,312
Noncash transfers from loans to other real estate	[1]	$ 12,115	8,760	23,965
Transfer of long-term FHLB advances to short-term			250,038	$ 500,009
Assets acquired in business combination			196,265
Liabilities assumed in business combination			$ 184,949

[1] Includes transfers from covered loans to foreclosed properties.