Loans - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Dec. 31, 2016
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	$ 78,268	$ 73,328
Provision for loan losses	4,050	1,500
Charge-offs	(5,574)	(5,458)
Recoveries	2,030	948
Ending balance	78,774	70,318
Allowance for loan losses
Loans individually evaluated for impairment			$ 5,640	$ 9,392
Loans collectively evaluated for impairment			73,134	68,876
Loans acquired with deteriorated credit quality			0	0
Total allowance for loan losses	78,268	73,328	78,774	78,268
Recorded investment (loan balance)
Loans individually evaluated for impairment			104,899	106,869
Loans collectively evaluated for impairment			7,854,870	7,351,532
Loans acquired with deteriorated credit quality			5,313,623	5,532,378
Total loans			13,273,392	12,990,779
Commercial loan portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	51,201	47,234
Provision for loan losses	4,392	1,000
Charge-offs	(2,691)	(3,896)
Recoveries	1,413	330
Ending balance	54,315	44,668
Allowance for loan losses
Loans individually evaluated for impairment			3,721	5,234
Loans collectively evaluated for impairment			50,594	45,967
Loans acquired with deteriorated credit quality			0	0
Total allowance for loan losses	51,201	47,234	54,315	51,201
Recorded investment (loan balance)
Loans individually evaluated for impairment			78,679	78,523
Loans collectively evaluated for impairment			4,353,210	4,026,526
Loans acquired with deteriorated credit quality			3,373,301	3,489,163
Total loans			7,805,190	7,594,212
Consumer loan portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	27,067	26,094
Provision for loan losses	(342)	500
Charge-offs	(2,883)	(1,562)
Recoveries	617	618
Ending balance	24,459	25,650
Allowance for loan losses
Loans individually evaluated for impairment			1,919	4,158
Loans collectively evaluated for impairment			22,540	22,909
Loans acquired with deteriorated credit quality			0	0
Total allowance for loan losses	$ 27,067	$ 26,094	24,459	27,067
Recorded investment (loan balance)
Loans individually evaluated for impairment			26,220	28,346
Loans collectively evaluated for impairment			3,501,660	3,325,006
Loans acquired with deteriorated credit quality			1,940,322	2,043,215
Total loans			$ 5,468,202	$ 5,396,567

Financing Receivable, Recorded Investment [Abstract]

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- Definition

Reserve for loans impairments recorded after acquisition as a result of current information and events which result in it being probable that estimated cash flows will be less than previously expected or because actual cash flows are less than cash flows previously expected. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

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- Definition

The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 310
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-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

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- References

No definition available.

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- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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Amount of direct write-downs of financing receivables charged against the allowance.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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- Definition

Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953423-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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