Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 9.0	$ 8.7
Cleven Litigation Case [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	54.6
Brown Litigation Case [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	$ 8.4
Apartment Communities [Member]
Loss Contingencies [Line Items]
Lease expiration year	2074
Office Lease [Member]
Loss Contingencies [Line Items]
Lease expiration year	2028

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14435-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12021-110248

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