Related-Party Transactions - Payable Balance with Affiliates (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	$ 6,184	$ 7,735
HOV Services, Ltd
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	367	405
Rule 14, LLC
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	110	127
HGM
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	5,450	6,998
Apollo
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	241	$ 205
Oakana Holdings Inc
Receivable and Payable Balances with Affiliates
Payable balances with affiliates	$ 16

Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

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 210.5-02.19(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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