Summary of Significant Accounting Policies - Schedule of Cash Flows Impact from ASUs Adoption (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) investing activities	$ 817,534	$ 1,740,698
Net increase (decrease) in balance	26,538	24,032
Cash, cash equivalents and restricted cash, beginning of period	82,203	136,990
Cash, cash equivalents and restricted cash, end of period	$ 108,741	161,022
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) investing activities		1,755,823
Net increase (decrease) in balance		39,157
Cash, cash equivalents and restricted cash, beginning of period		94,730
Cash, cash equivalents and restricted cash, end of period		$ 133,887

Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including, but not limited to, disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3044-108585

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