Uniform Net Capital Rule Requirements - Narrative (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($) subsidiary	Dec. 31, 2017 USD ($)
Uniform Net Capital Rule Requirements
Number of subsidiaries registered as broker dealers \| subsidiary	2
Maximum ratio of aggregate indebtedness to net capital	15.0
Minimum net capital \| $	$ 250	$ 250
Net capital percentage of debit balances	2.00%	2.00%

This element represents the amount of net capital of a broker or dealer that has elected not to be subject to the Aggregate Indebtedness Standard (as defined). The amount of net capital represented by this element is the greater of $250,000 or two percent of aggregate debit items computed in accordance with the Formula for Determination of Reserve Requirements for Brokers and Dealers (as defined).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

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