Acquired Loans - Changes in the Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Apr. 07, 2017
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		$ 260,850
Accretion to interest income		11,021	$ 14,351
Carrying value, net, ending		277,989		$ 260,850
Additions					$ 7,900
Acquired Not ASC 310-30 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	42,743	67,657	67,657
Accretion to interest income	[1]	1,159		40
Payments received, net	[1]	(29,266)		(24,953)
Other	[1],[2]	1,220		0
Change in allowance for loan losses, acquired loans	[1]	0		(1)
Carrying value, net, ending	[1]	88,685		42,743
Transfers	[1],[3]	(36,719)
Additions	[1],[4]	109,548
Acquired Impaired [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		218,107	$ 310,762	310,762
Accretion to interest income		11,021		18,405
Payments received, net		(50,406)		(111,522)
Other	[2]	(2,946)		(134)
Change in allowance for loan losses, acquired loans		5,629		596
Carrying value, net, ending		189,304		$ 218,107
Transfers	[3]	0
Additions	[4]	$ 7,899

[1] "Acquired Not ASC 310-30" loans consist of loans that are not in scope for FASB ASC Topic 310-30, "Loans and Debt Securities Acquired with Deteriorated Credit Quality."

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

[3] “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized.

[4] Loans acquired in the Reliance merger on April 7, 2017.