Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details)		9 Months Ended	12 Months Ended
	May 21, 2009 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) county branch banking_center subsidiary bank	Dec. 31, 2015 USD ($)
Summary of Significant Accounting Policies [Line Items]
Subsidiary | subsidiary			1
Number of branches located in Florida (in Branches) | branch			94
Number of Florida counties with branches (in counties) | county			15
Number of branches located in New York metropolitan area (in Branches) | banking_center			6
Number of loss sharing agreements	2
Percent FDIC will reimburse for covered losses (in Percent)	80.00%
Limit on losses reimbursed at 80%	$ 4,000,000,000
Percent of losses in excess of limit FDIC will reimburse (in Percent)	95.00%
Period of delinquency of principal or interest at which new and non-ACI commercial loans are placed on non-accrual status unless the loan is well-secured and in the process of collection (in Duration)			90 days
Period of delinquency of interest at which new and non-ACI residential and consumer loans are placed on non-accrual status unless the loan is well-secured and in the process of collection (in Duration)			90 days
Period of principal or interest paid at which new and non-ACI residential loans are returned to accrual status (in Duration)			90 days
Maximum period of loans past due reported as current (in Duration)			30 days
The value at which non accrual status commercial relationships are evaluated for impairment			$ 1,000,000
Period of no missed payments, borrower exempt from troubled-debt restructuring (in Duration)			6 months
Period pursuant to modified loan terms of borrower compliance loan is returned to accrual status (in Duration)			6 months
Minimum period of delinquency for new open- and closed-end loans secured by residential real estate, at which an assessment of collateral value is made (in Duration)			120 days
Minimum period of delinquency of any outstanding loan balance in excess of fair value less cost to sell, at which it is charged off (in Duration)			180 days
Period after receipt of notification of filing from the bankruptcy court at which any outstanding balance in excess of fair value of collateral less cost to sell, at which it is charged off (in Duration)			60 days
Period within determination of loss if all borrowers are deceased, at which any outstanding balance in excess of fair value of collateral less cost to sell, at which it is charged off (in Duration)			60 days
Period within days of discovery of fraudulent activity, at which any outstanding balance in excess of fair value of collateral less cost to sell, at which it is charged off (in Duration)			90 days
Period of delinquency of consumer loans, at which, at which they are charged off when management deems them to be uncollectible (in Duration)			120 days
Percent of loss severity assumption for home equity loans and lines of credit projected to roll to 120 days delinquency (in Percent)			100.00%
Period of delinquency at which 100% loss severity is assumed (in Duration)			120 days
Loans and Leases Receivable, Loss Emergence Period			1 year
Loans and Leases Receivable, Loss Experience Period in quarters for commercial loans			4 years
Loans and Leases Receivable, Loss Emergence Period in quarters for municipal loans and leases			3 years
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		$ 9,000,000
Loans and Leases Receivable, Net Charge-Off Rate Calculation, Banks Used In Assumption | bank			27
Goodwill			$ 78,000,000	$ 78,000,000
Percentage floor, after which the likelihood that the tax benefit related to uncertain tax positions are measured (in Percent)			50.00%
Fees and Commissions, Depositor Accounts			$ 13,000,000
Investment securities available for sale, at fair value			6,073,584,000	4,859,539,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax			$ 103,806,000	$ 94,856,000
Building and Building Improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			30 years
Minimum | Leasehold Improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			5 years
Minimum | Furniture, Fixtures And Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			5 years
Minimum | Computer Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			3 years
Minimum | Software and Software Development Costs [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			3 years
Maximum [Member] | Leasehold Improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			20 years
Maximum [Member] | Furniture, Fixtures And Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			7 years
Maximum [Member] | Computer Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			5 years
Maximum [Member] | Software and Software Development Costs [Member]
Summary of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			5 years
NEW YORK
Summary of Significant Accounting Policies [Line Items]
Loans and Leases Receivable, Net Charge-Off Rate Calculation, Banks Used In Assumption | bank			2