Significant Accounting Policies Contingent Consideration (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Combination Contingent Liability [Roll Forward]
Beginning balance	$ 0
Change in fair value of contingent consideration	1,100	$ 0	$ 0
Ending balance	45,100	0
Viventia Bio Inc.
Business Combination Contingent Liability [Roll Forward]
Beginning balance	0
Contingent consideration from acquisition of Viventia Bio Inc.	46,200
Change in fair value of contingent consideration	(1,100)
Ending balance	$ 45,100	$ 0