The cumulative difference between the rental payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense over the term of the leased property by the lessor or lessee, respectively.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of lessee's right to use underlying asset under operating lease.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Leases - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating lease right of use assets	$ 16,185
Operating lease liabilities	$ 20,188
Deferred Rent Credit			$ 4,000
Operating leases			$ 18,034
Accounting Standards Update 2016-02 [Member]
Operating lease right of use assets		$ 17,000
Operating lease liabilities		$ 21,000