Summary of Significant Accounting Policies - Early Adoption (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities	$ 99,996	$ 163,703	$ 188,114
Cash provided by investing activities	465,586	1,025,719	1,852,602
Cash used in financing activities	$ (306,198)	(923,182)	(593,013)
ASU 2016-18 and ASU 2016-15
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities		163,703	188,114
Cash provided by investing activities		1,025,719	1,852,602
Cash used in financing activities			(593,013)
ASU 2016-18 and ASU 2016-15 \| Originally Reported
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities		163,016	181,544
Cash provided by investing activities		1,052,119	1,648,893
Cash used in financing activities			(382,722)
ASU 2016-18 and ASU 2016-15 \| Effect of Change
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities		687	6,570
Cash provided by investing activities		$ (26,400)	203,709
Cash used in financing activities			$ (210,291)

Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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- Definition

Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

+ References

+ Details

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- Definition

Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3521-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3536-108585

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+ References

No definition available.

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