Acquisitions (Schedule of Fair Value of Net Assets Acquired) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Apr. 28, 2017	Mar. 10, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 739,403			$ 621,193
FNBC Transaction [Member]
Business Acquisition [Line Items]
Cash and due from banks	160,788
Interest-bearing time deposits with other banks	382,622
Fed funds sold and other short-term investments	148
Securities	213,877
Total Loans	1,377,100
Property and equipment	20,825
Accrued interest receivable	3,854
Identifiable intangible assets	25,300
Other assets	4,213
Total identifiable assets	2,188,727
Deposits	1,928,509
Short-term borrowings	596,635
Long-term debt	93,120
Other liabilities	4,686
Total liabilities	2,622,950
Net identifiable assets acquired (liabilities assumed)	(434,223)
Consideration (Paid) Received	316,013
Goodwill	$ 118,210
FNBC I [Member]
Business Acquisition [Line Items]
Cash and due from banks			$ 2,856
Total Loans			1,211,523
Property and equipment			11,837
Accrued interest receivable			2,969
Identifiable intangible assets			3,900
Other assets			63
Total identifiable assets			1,233,148
Deposits			398,171
Short-term borrowings			510,749
Long-term debt			93,120
Other liabilities			1,607
Total liabilities			1,003,647
Net identifiable assets acquired (liabilities assumed)			229,501
Consideration (Paid) Received			(325,564)
Goodwill			$ 96,063
FNBC II [Member]
Business Acquisition [Line Items]
Cash and due from banks		$ 157,932
Interest-bearing time deposits with other banks		382,622
Fed funds sold and other short-term investments		148
Securities		213,877
Total Loans		165,577
Property and equipment		8,988
Accrued interest receivable		885
Identifiable intangible assets		21,400
Other assets		4,150
Total identifiable assets		955,579
Deposits		1,530,338
Short-term borrowings		85,886
Other liabilities		3,079
Total liabilities		1,619,303
Net identifiable assets acquired (liabilities assumed)		(663,724)
Consideration (Paid) Received		641,577
Goodwill		$ 22,147