Significant Accounting Policies (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017 USD ($) branches ATM	Jun. 30, 2017 USD ($) branches ATM	Dec. 31, 2016 USD ($)
Basis Of Presentation [Line Items]
Number of branches | branches	248	248
Number of ATMs | ATM	327	327
Share-based compensation, excess tax benefit	$ 378	$ 4,500
Cash and Cash Equivalents
Basis Of Presentation [Line Items]
Total deposits	0	0	$ 533
Cash and cash equivalents	120,500	120,500	130,000
Interest earning deposits with banks	5,900	5,900	5,600
Federal funds sold	$ 43,300	$ 43,300	$ 56,100