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Summary of Significant Accounting Policies - Income Taxes (Detail) | 6 Months Ended
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Jun. 30, 2017 USD ($)
Income Taxes [Line Items] |
Total amount of unrecognized tax benefits relating to uncertain tax positions | $ 36,300,000
Amount of unrecognized tax benefits change from year end relating to uncertain tax positions | 1,100,000
Maximum |
Income Taxes [Line Items] |
Reasonably possible reduction to the balance of unrecognized tax benefits in succeeding 12 months | $ 13,400,000.0

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- Definition Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (d)(3) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32718-109319 + Details
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