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Balance Sheet Information - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Mar. 31, 2019 | Mar. 31, 2018
Balance Sheet Related Disclosures [Abstract] |  |  |  |
Depreciation expense | $ 18.8 | $ 15.6 | $ 36.9 | $ 31.4
Amortization of unfavorable lease liability | $ 1.5 | $ 1.7 | $ 3.1 | $ 3.4

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- Definition Amortization of unfavorable lease liability. + References No definition available. + Details
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Balance Type: | credit
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- References No definition available. + Details
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- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
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