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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Segment Information - Additional Information (Details) $ in Millions			12 Months Ended
	Jan. 01, 2021 Segment	Jun. 01, 2020 USD ($)	Dec. 31, 2020 Segment	Sep. 30, 2019 USD ($)	May 23, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of operating business segments \| Segment			4
Sale of portfolio, cash consideration \| $				$ 2.9	$ 30.7
United States \| Tower \| Melody Investment Advisors
Segment Reporting Information [Line Items]
Sale of portfolio, cash consideration \| $		$ 225.8
Investment interest retained, percentage		10.00%
Subsequent Event
Segment Reporting Information [Line Items]
Number of operating business segments \| Segment	2