Business Segments - Additional Information (Detail) - Segment	1 Months Ended	12 Months Ended
Aug. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Number of reportable segments		3
Mariner Finance, LLC
Segment Reporting Information [Line Items]
Stock purchase agreement, stock sold, percentage	100.00%

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

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