Noncontrolling Interests - Additional Information (Details) $ in Millions	Dec. 31, 2017 USD ($) entity	Dec. 31, 2016 USD ($)
Noncontrolling Interest [Abstract]
Number of VIEs \| entity	5
Total assets of variable interest entities	$ 5.6	$ 8.0
Total liabilities and noncontrolling interest of variable interest entities	$ 5.8	$ 7.2

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=77990344&loc=d3e5710-111685

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