Annual report pursuant to Section 13 and 15(d)

Financial Instruments Financial Instruments - Additional Information (Details 4)

v3.6.0.2
Financial Instruments Financial Instruments - Additional Information (Details 4)
 9 Months Ended 12 Months Ended
Sep. 30, 2016
Dec. 31, 2016
USD ($)
debt_security
Dec. 31, 2015
USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Fair Value, Liabilities, Transfers between Levels   $ 0  
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount   $ 0  
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | debt_security   25  
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value   $ 42,200,000  
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax   39,000 $ 114,000
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount   0  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net   $ 0  
Minimum [Member]      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Available For Sale Securities Non Current Maturity Period 1 year    
Maximum [Member]      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Period Of Unrealized Loss Position   12 months  
Available For Sale Securities Non Current Maturity Period 2 years    
Maximum [Member] | Fair Value, Inputs, Level 3 [Member]      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Fair Value Inputs, Discount Rate   1.00% 0.41%
Investments [Member]      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax   $ 39,000 $ 114,000