The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Recent Accounting Pronouncements Adopted by the Company
Distributions received from joint ventures	$ 190
Distributions received from joint ventures	5,540	$ 1,880
ASU 2016-15
Recent Accounting Pronouncements Adopted by the Company
Distributions received from joint ventures		(1,900)
Distributions received from joint ventures		$ 1,900
ASU 2018-15
Recent Accounting Pronouncements Adopted by the Company
Capitalized costs	$ 1,000		$ 0