Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
Apr. 13, 2016	Feb. 23, 2016	Mar. 31, 2016	Mar. 31, 2015
Shareholders' Equity
Distribution to common shareholders (in dollars per share)	$ 0.39	$ 0.39
Distribution to common shareholders	$ 92,614	$ 92,614	$ 92,614	$ 79,530

Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration