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Significant Accounting Policies, Convertible Debt and Segment Information (Details) - Segment
3 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Segment Information [Abstract]    
Number of operating segments 2  
1 Percent Convertible Senior Notes [Member]    
Convertible Debt [Abstract]    
Interest rate on convertible senior notes 1.00% 1.00%
2 3/4 Percent Convertible Senior Notes [Member]    
Convertible Debt [Abstract]    
Interest rate on convertible senior notes 2.75%