Leases - Additional Information (Details) $ in Millions	Jun. 30, 2019 USD ($) renewal_option	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 5		$ 0
Operating lease liability	$ 5
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 5
Operating lease liability		$ 5
Ten Year Agreement, Five Year Renewal Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Initial term	10 years
Additional term	5 years
Number of options to extend | renewal_option	2
Ten Year Agreement, One Year Renewal Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Initial term	10 years
Additional term	1 year
Number of options to extend | renewal_option	10