Common Stock - Additional Information (Detail) - Underwritten Public Offering [Member] $ / shares in Units, $ in Millions	1 Months Ended
Feb. 28, 2018 USD ($) $ / shares shares
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares) \| shares	13,269,230
Offering price (in dollars per share) \| $ / shares	$ 52.00
Net proceeds from stock offering \| $	$ 658.2

Number of new stock issued during the period.

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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
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-Name Accounting Standards Codification
-Topic 505
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration