Commitments and Contingencies - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finance lease cost:
Finance lease cost, amortization of right-of-use assets	$ 11,884	$ 11,029	$ 11,252
Finance lease cost, interest on lease liabilities	676	640	889
Operating lease cost	10,467	10,177	9,380
Short-term lease cost	732	493	1,103
Variable lease cost	3,112	2,502	2,173
Sublease income	(572)	(24)	(79)
Total lease cost	$ 26,299	$ 24,817	$ 24,718

No definition available.

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- Definition

Amount of interest expense on finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

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-Publisher FASB
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- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

+ References

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Amount of sublease income excluding finance and operating lease expense.

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- Definition

Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

+ References

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