Summary of Significant Accounting Policies (Equity Based Compensation) (Details) - RSUs	36 Months Ended	51 Months Ended
Dec. 31, 2013	Mar. 31, 2018
Share based compensation
Vesting period of restricted share units (RSUs)		3 years
Period for measuring market condition of award	3 years	3 years
Minimum
Share based compensation
Vesting period of restricted share units (RSUs)	1 year
Maximum
Share based compensation
Vesting period of restricted share units (RSUs)	3 years

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration