Mergers and Acquisitions Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Labor and Related Expense	$ 48,072	$ 37,220	$ 32,669
Equipment And Software Expense	9,557	8,057	7,316
Occupancy, Net	7,088	5,695	5,055
Professional Fees	3,234	2,625	2,368
Other Noninterest Expense	10,687	9,210	7,845
Business Combination, Acquisition Related Costs	866	10,415	0
SBM Financial, Inc. [Member]
Business Acquisition [Line Items]
Labor and Related Expense	8	3,240
Equipment And Software Expense	279	1,531
Occupancy, Net	439	1,237
Professional Fees	80	2,453
Other Noninterest Expense	60	1,954
Business Combination, Acquisition Related Costs	$ 866	$ 10,400	0
Business Acquisition One [Member]
Business Acquisition [Line Items]
Labor and Related Expense			0
Equipment And Software Expense			0
Occupancy, Net			0
Professional Fees			0
Other Noninterest Expense			$ 0