Common stock special dividends per share declared.

No definition available.

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Namespace Prefix:	mc_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the per share amount of a special dividend paid during the reporting period.

+ References

No definition available.

+ Details

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Namespace Prefix:	mc_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the declared dividend will be paid, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the dividend to be paid was declared, in CCYY-MM-DD format.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Details

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- Details

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Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 05, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 27, 2019	Mar. 31, 2015
Class A Common Stock
Subsequent Event [Line Items]
Dividends declared per share		$ 4.88	$ 2.48	$ 3.29
Share value authorized for repurchase						$ 25.0
Subsequent Event
Subsequent Event [Line Items]
Special dividends paid (in dollars per share)	$ 1.25
Dividends declared per share	0.50
Total quarterly and special dividends declared per share	$ 1.75
Dividend declared date	Feb. 05, 2019
Dividend payable date	Mar. 29, 2019
Dividend payable record date	Feb. 19, 2019
Share value authorized for repurchase					$ 3.5
Subsequent Event \| Maximum \| Class A Common Stock
Subsequent Event [Line Items]
Share value authorized for repurchase					$ 100.0