Represents the percentage of revenues impacted by the new accounting pronouncement.

No definition available.

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- Definition

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

+ References

No definition available.

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- Definition

Amount of the cumulative effect on retained earnings net of related income tax effect.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 250
-SubTopic 10
-Section 50
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- Definition

Amount of lessee's undiscounted obligation for lease payments for operating lease.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
New Accounting Pronouncements
Other income	$ 1,399,814	$ 1,345,763
Retained Earnings (Accumulated Deficit)	(4,774,442)		$ (4,782,173)
Accounting Standards Update 2014-09 \| Maximum
New Accounting Pronouncements
Percentage of revenues impacted by ASU (as a percent)			6.00%	7.00%
Accounting Standards Update 2014-09 \| Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements
Retained Earnings (Accumulated Deficit)					$ 0
Accounting Standards Update 2016-01
New Accounting Pronouncements
Cumulative effect on retained earnings	7,264
Accounting Standards Update 2016-01 \| Adjustment
New Accounting Pronouncements
Cumulative effect on retained earnings	7,300
Accounting Standards Update 2016-02 \| Scenario Forecast Adjustment
New Accounting Pronouncements
Future minimum gross lease payments	$ 780,400
Accounting Standards Update 2017-05 \| Adjustment
New Accounting Pronouncements
Cumulative effect adjustment					$ 0