Annual report pursuant to Section 13 and 15(d)

Fair Value of Assets and Liabilities (Schedule of Fair Value of Assets and Liabilities Measured on a Recurring Basis) (Details)

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Fair Value of Assets and Liabilities (Schedule of Fair Value of Assets and Liabilities Measured on a Recurring Basis) (Details) - Fair Value, Measurements, Recurring - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Carrying Value    
Assets    
Total assets $ 3,881 $ 3,543
Liabilities    
Contingent consideration payable 2,104 7,144
Total liabilities 2,335 7,526
Carrying Value | Debt securities    
Assets    
Other investments 1,918 1,850
Liabilities    
Liabilities 151 25
Carrying Value | U.S. Treasury notes    
Assets    
Other investments 0 101
Liabilities    
Liabilities 0 96
Carrying Value | Common stock and warrants    
Assets    
Other investments 1,395 1,149
Liabilities    
Liabilities 80 261
Fair Value    
Assets    
Total assets 3,881 3,543
Liabilities    
Contingent consideration payable 2,104 7,144
Total liabilities 2,335 7,526
Fair Value | Level 1    
Assets    
Total assets 1,333 937
Liabilities    
Contingent consideration payable 0 0
Total liabilities 80 261
Fair Value | Level 2    
Assets    
Total assets 2,548 2,606
Liabilities    
Contingent consideration payable 0 0
Total liabilities 151 121
Fair Value | Level 3    
Assets    
Total assets 0 0
Liabilities    
Contingent consideration payable 2,104 7,144
Total liabilities 2,104 7,144
Fair Value | Debt securities    
Assets    
Other investments 1,918 1,850
Liabilities    
Liabilities 151 25
Fair Value | Debt securities | Level 1    
Assets    
Other investments 0 0
Liabilities    
Liabilities 0 0
Fair Value | Debt securities | Level 2    
Assets    
Other investments 1,918 1,850
Liabilities    
Liabilities 151 25
Fair Value | Debt securities | Level 3    
Assets    
Other investments 0 0
Liabilities    
Liabilities 0 0
Fair Value | U.S. Treasury notes    
Assets    
Other investments 0 101
Liabilities    
Liabilities 0 96
Fair Value | U.S. Treasury notes | Level 1    
Assets    
Other investments 0 0
Liabilities    
Liabilities 0 0
Fair Value | U.S. Treasury notes | Level 2    
Assets    
Other investments 0 101
Liabilities    
Liabilities 0 96
Fair Value | U.S. Treasury notes | Level 3    
Assets    
Other investments 0 0
Liabilities    
Liabilities 0 0
Fair Value | Common stock and warrants    
Assets    
Other investments 1,395 1,149
Liabilities    
Liabilities 80 261
Fair Value | Common stock and warrants | Level 1    
Assets    
Other investments 765 494
Liabilities    
Liabilities 80 261
Fair Value | Common stock and warrants | Level 2    
Assets    
Other investments 630 655
Liabilities    
Liabilities 0 0
Fair Value | Common stock and warrants | Level 3    
Assets    
Other investments 0 0
Liabilities    
Liabilities 0 0
Certificates of deposit | Carrying Value    
Assets    
Cash and cash equivalents 568 443
Certificates of deposit | Fair Value    
Assets    
Cash and cash equivalents 568 443
Certificates of deposit | Fair Value | Level 1    
Assets    
Cash and cash equivalents 568 443
Certificates of deposit | Fair Value | Level 2    
Assets    
Cash and cash equivalents 0 0
Certificates of deposit | Fair Value | Level 3    
Assets    
Cash and cash equivalents $ 0 $ 0