Fair Value Measurement of Convertible Senior Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities
Convertible senior notes, net	$ 281,589	$ 270,192

Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Convertible Security
-URI http://asc.fasb.org/extlink&oid=6509036

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