Basis of presentation and significant accounting policies.

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Regulatory milestone payment.

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- Definition

Amount of direct write-downs of accounts receivable charged against the allowance.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of increase (decrease) in cash, cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including effect from exchange rate change. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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The amount of a reclassification adjustment made to prior period financial statement amounts.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Basis Of Presentation And Significant Accounting Policies [Line Items]
Net cash used in operations				$ (128,391,000)	$ (187,862,000)
Net decrease in cash and cash equivalents				(4,885,000)	(50,904,000)
Accounts receivable written off				0	0
One-time contingent regulatory milestone payment pursuant to agreement with Ipsen Group	$ 8,000,000
Finite-lived intangible assets, net	$ 8,000,000
Amortization of intangible assets		$ 400,000	$ 400,000	1,107,000	1,108,000
Estimated future amortization expense, remainder of 2018		400,000		400,000
Estimated future amortization expense, 2019		1,500,000		1,500,000
Estimated future amortization expense, 2020		1,500,000		1,500,000
Estimated future amortization expense, 2021		1,000,000		1,000,000
Revenue recognition		(1,403,371,000)		(1,403,371,000)			$ (1,223,671,000)
ASU 2016-18
Basis Of Presentation And Significant Accounting Policies [Line Items]
Net cash used in operations					100,000
Net decrease in cash and cash equivalents					100,000
Topic 606
Basis Of Presentation And Significant Accounting Policies [Line Items]
Cumulative-effect adjustment to retained earnings						$ 0
Topic 606 \| Difference effect of change - higher (lower)
Basis Of Presentation And Significant Accounting Policies [Line Items]
Revenue recognition		$ 0		$ 0
Selling, general and administrative expense
Basis Of Presentation And Significant Accounting Policies [Line Items]
Prior period reclassification adjustment			700,000		1,200,000
Total operating expense
Basis Of Presentation And Significant Accounting Policies [Line Items]
Prior period reclassification adjustment			$ 700,000		$ 1,200,000