Summary of Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accounting Policies [Abstract]
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued	[1]			0	1,858,133,000
Cash Transactions:
Interest paid				$ 82,321,000	$ 29,311,000
Income taxes paid, net				28,105,000	25,036,000
Noncash Transactions:
Loans charged-off to the allowance for loan losses		$ 6,698,000	$ 5,157,000	15,367,000	10,321,000
Loans foreclosed upon and transferred to other real estate owned				1,505,000	1,520,000
Loans foreclosed upon and transferred to other assets				$ 950,000	$ 446,000

[1] See Note 2 to these consolidated financial statement for more detailed information.