3.   Revenue Recognition

Disaggregation of Revenue

Revenue and cash flows are affected by economic factors in various geographical regions. Revenues by destination were as follows (in thousands):

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North America includes the U.S., the Caribbean, Canada and Mexico. Europe includes the Baltic region, Canary Islands and Mediterranean. Asia-Pacific includes Australia, New Zealand and Asia. Other includes all other international territories.

Segment Reporting

We have concluded that our business has a single reportable segment. Each brand, Norwegian, Oceania Cruises and Regent, constitutes a business for which discrete financial information is available and management regularly reviews the brand level operating results and, therefore, each brand is considered an operating segment. Our operating segments have similar economic and qualitative characteristics, including similar long-term margins and similar products and services; therefore, we aggregate all of the operating segments into one reportable segment.

Although we sell cruises on an international basis, our passenger ticket revenue is primarily attributed to U.S.-sourced guests who make reservations in the U.S. Revenue attributable to U.S.-sourced guests has historically approximated 75-80%. No other individual country’s revenues exceed 10% in any given period.

Contract Balances

Receivables from customers are included within accounts receivables, net. As of June 30, 2019 and December 31, 2018, our receivables from customers were $19.4 million and $17.3 million, respectively.

Our contract liabilities are included within advance ticket sales. As of June 30, 2019 and December 31, 2018, our contract liabilities were $1.7 billion and $1.2 billion, respectively. Of the amounts included within contract liabilities, approximately 50% were refundable in accordance with our cancellation policies. For the six months ended June 30, 2019, $1.2 billion of revenue recognized was included in the contract liability balance at the beginning of the period.