XML 54 R42.htm IDEA: XBRL DOCUMENT v3.8.0.1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES. (Property and equipment) (Details)	12 Months Ended
	Dec. 31, 2017
Computer and communications software and equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	32 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	8 years
Furniture and other equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Leased land [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	99 years

X

- 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

Name:	us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=trow_ComputerAndCommunicationsSoftwareAndEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingAndBuildingImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LeaseholdImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FurnitureAndFixturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=trow_LeasedLandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: