Commitments and Contingencies (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Other Commitments [Line Items]
Operating lease agreements due in next twelve months	$ 2,952
Operating lease agreements due in year two	16,146
Operating lease agreements due in year three	16,108
Operating lease agreements due in year four	16,512
Operating lease agreements due in year five	16,387
Operating lease agreements due thereafter	26,128
Other Contractual Arrangements
Other Commitments [Line Items]
Operating lease agreements due in next twelve months	100
Operating lease agreements due in year two	600
Operating lease agreements due in year three	800
Operating lease agreements due in year four	800
Operating lease agreements due in year five	800
Operating lease agreements due thereafter	5,400
Letter of Credit | Other Contractual Arrangements
Other Commitments [Line Items]
Letters of credit outstanding	$ 7,600	$ 7,700