Quarterly Data (Unaudited) - Tax Benefit from Sale of New Jersey State Net Operating Losses (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
New Jersey \| Sale of unused NOLs and research and development credits
Sale of New Jersey Net Operating Losses
Tax benefit	$ 0.5	$ 3.1

Amount of current state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
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-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration