Acquired Loans - Changes in the Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Carrying value of acquired loans [Abstract]
Accretion to interest income		$ 30,501	$ 48,627
Noncovered Loans [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		515,242
Carrying value, net, ending		361,452	515,242
Covered Loans [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		22,108
Carrying value, net, ending		16,967	22,108
Acquired Not ASC 310-30 [Member] | Noncovered Loans [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	81,091	123,085
Accretion to interest income	[1]	479	1,706
Payments received, net	[1]	(15,484)	(42,284)
Other	[1],[2]	0	(2,102)
Less change in allowance for loan losses, acquired loans	[1]	0	686
Carrying value, net, ending	[1]	66,086	81,091
Acquired Not ASC 310-30 [Member] | Covered Loans [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	1,604	1,663
Accretion to interest income	[1]	0	1
Payments received, net	[1]	(33)	(30)
Other	[1],[2]	0	(484)
Less change in allowance for loan losses, acquired loans	[1]	0	454
Carrying value, net, ending	[1]	1,571	1,604
Acquired Impaired [Member] | Noncovered Loans [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		434,151	639,656
Accretion to interest income		28,193	44,575
Payments received, net		(164,671)	(216,378)
Other	[2]	(1,589)	(29,724)
Less change in allowance for loan losses, acquired loans		(718)	(3,978)
Carrying value, net, ending		295,366	434,151
Acquired Impaired [Member] | Covered Loans [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		20,504	30,166
Accretion to interest income		2,308	4,052
Payments received, net		(8,592)	(12,396)
Other	[2]	391	(1,733)
Less change in allowance for loan losses, acquired loans		785	415
Carrying value, net, ending		$ 15,396	$ 20,504

[1] (1) "Acquired Not ASC 310-30" loans consist of revolving credit agreements and commercial leases that are not in scope for FASB ASC Topic 310-30.

[2] (1) Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off, pool recovery and other terminations.