Loans and the Allowance for Loan Losses - (Details 10) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Certain Loans Acquired In Transfer Accounted For As Debt Securities Accretable Yield Movement Schedule Roll Forward
Balance at January 1, 2015	$ (32,433)
Additions due to acquisition	(20,266)
Reclasses from nonaccretable difference	(3,956)
Accretion	11,250
Charge-offs	1,483
Balance at September 30, 2015	(43,922)
Impaired Covered Loans
Certain Loans Acquired In Transfer Accounted For As Debt Securities Accretable Yield Movement Schedule Roll Forward
Balance at January 1, 2015	(1)
Additions due to acquisition	0
Reclasses from nonaccretable difference	(578)
Accretion	569
Charge-offs	0
Balance at September 30, 2015	(10)
Other Covered Loans
Certain Loans Acquired In Transfer Accounted For As Debt Securities Accretable Yield Movement Schedule Roll Forward
Balance at January 1, 2015	(2,623)
Additions due to acquisition	(4,880)
Reclasses from nonaccretable difference	977
Accretion	1,550
Charge-offs	0
Balance at September 30, 2015	(4,976)
Not Covered Loans
Certain Loans Acquired In Transfer Accounted For As Debt Securities Accretable Yield Movement Schedule Roll Forward
Balance at January 1, 2015	(29,809)
Additions due to acquisition	(15,386)
Reclasses from nonaccretable difference	(4,355)
Accretion	9,131
Charge-offs	1,483
Balance at September 30, 2015	$ (38,936)