Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014 segment	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Number of operating segments	2us-gaap_NumberOfOperatingSegments
Impairment of goodwill	$ 0us-gaap_GoodwillImpairmentLoss
Amounts due from financial intermediaries classified as cash and cash equivalents	805,000	1,623,000
Allowance for doubtful accounts	61,000	104,000
Advertising expense	$ 121,092,000us-gaap_AdvertisingExpense	$ 86,165,000us-gaap_AdvertisingExpense	$ 66,049,000us-gaap_AdvertisingExpense
Minimum
Income Tax Contingency [Line Items]
Percentage of tax benefit likely to be realized upon settlement	50.00%

Percentage of tax benefit likely to be realized upon settlement.

No definition available.

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- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 720

-SubTopic 35

-Section 50

-Paragraph 1

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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 4

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 4

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.4)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount due the Entity as a result of customers utilizing point of sale debit or credit cards in exchange transactions with the entity which are short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

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- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

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-Paragraph 2

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-Name Accounting Standards Codification

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-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

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