Loans and Allowance for Loan Losses (Details 4) - Acquired loans - Credit impaired - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014
Changes in the carrying value of acquired loans at the acquisition date
Balance at the beginning of the period		$ 919,402	$ 1,220,638
Net reductions for payments, foreclosures, and accretion		(153,687)	(243,732)
Change in the allowance for loan losses on acquired loans		2,891	3,586
Balance at the end of the period	$ 768,606	768,606	980,492
Changes in the carrying amount of accretable difference for acquired impaired and non-impaired loans
Balance at beginning of period		306,826	301,516
Accretion		(76,168)	(79,579)
Reclass of nonaccretable difference due to improvement in expected cash flows	23,600	39,030	46,960
Other changes, net		(69,674)	(2,679)
Balance at end of period	200,014	200,014	$ 266,218
Decline in accretable yield balance	$ 24,900	64,100
Impairment of acquired loans		$ 0