Related-Party Transactions - Receivable and Payable Balance with Affiliates (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Receivable and Payable Balances with Affiliates
Receivable balances with affiliates	$ 206	$ 0
Payable balances with affiliates	238	7,735
HOV Services, Ltd
Receivable and Payable Balances with Affiliates
Receivable balances with affiliates	189
Payable balances with affiliates		405
Rule 14, LLC
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	145	127
HGM
Receivable and Payable Balances with Affiliates
Receivable balances with affiliates	17
Payable balances with affiliates		6,998
Apollo
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	91	$ 205
Oakana Holdings Inc
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	$ 2

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(11))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Name:	us-gaap_DueFromRelatedPartiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant