Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
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+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
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- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 15
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-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

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Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument Fee Percentage

+ References

No definition available.

+ Details

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- Definition

The remaining balance of debt issuance costs associated with the revolving credit facility that are being amortized against income over its life.

+ References

No definition available.

+ Details

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Credit Facility - Additional Information (Detail) - USD ($)		12 Months Ended
	Apr. 11, 2018	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Proceeds from term loan		$ 0	$ 200,000,000
Interest expense		11,240,000	7,962,000
Unamortized issuance costs		671,000	1,195,000
Long-term debt, fair value		176,986,000	$ 196,126,000
Repayment of long-term debt		$ 21,000,000
Acquisition of ETFS Business [Member] \| Term Loan Facility [Member]
Debt Instrument [Line Items]
Proceeds from term loan	$ 200,000,000
Debt instrument, interest rate		Interest on the Term Loan accrues at an annual rate equal to LIBOR, plus up to 2.00% (commencing at LIBOR, plus 1.75%)
Debt instrument, variable rate basis		LIBOR
Acquisition of ETFS Business [Member] \| Term Loan Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	1.75%
Acquisition of ETFS Business [Member] \| Term Loan Facility [Member] \| Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	2.00%
Acquisition of ETFS Business [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		Revolver accrues at an annual rate equal to LIBOR, plus up to 1.50% (commencing at LIBOR, plus 1.25%)
Debt instrument, variable rate basis		LIBOR
Revolving credit facility maximum borrowing capacity	$ 50,000,000
Debt instrument, facility fee rate	0.50%
Acquisition of ETFS Business [Member] \| Revolving Credit Facility [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	1.25%
Acquisition of ETFS Business [Member] \| Revolving Credit Facility [Member] \| Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	1.50%