Fair Value Measurements - Level 3 Significant Unobservable Inputs (Detail) - Fair Value, Measurements, Recurring - LEVEL 3 - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Auction Rate \| Group One
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
UNOBSERVABLE INPUT		Price
Visa Conversion Rate Swap
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, fair value	$ 32.8	$ 29.7
Visa Conversion Rate Swap \| Group One
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
UNOBSERVABLE INPUT	Visa Class A Appreciation	Visa Class A Appreciation
Visa Conversion Rate Swap \| Group Two
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
UNOBSERVABLE INPUT	Conversion Rate	Conversion Rate
Visa Conversion Rate Swap \| Group Three
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
UNOBSERVABLE INPUT	Expected Duration	Expected Duration
Visa Conversion Rate Swap \| Lower Limit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Visa Class A Appreciation	7.00%	7.00%
Conversion Rate	1.62%	1.63%
Expected Duration	1 year 6 months	1 year 6 months
Visa Conversion Rate Swap \| Upper Limit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Visa Class A Appreciation	11.00%	11.00%
Conversion Rate	1.64%	1.65%
Expected Duration	4 years	4 years
Auction Rate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, fair value		$ 4.3
Auction Rate \| Lower Limit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial instrument price (in dollars per share)		$ 92
Auction Rate \| Upper Limit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial instrument price (in dollars per share)		$ 100

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Financial Instruments Fair Value Assumptions Price Per Share

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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