Revenue Recognition and Related Costs	12 Months Ended
Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition and Related Costs	Revenue Recognition and Related Costs Contract Balances If we transfer goods or services to a customer but do not have an unconditional right to payment, we record a contract asset. Contract assets typically arise from the uniform recognition of introductory promotional discounts over the contract period and accrued revenue for handset sales. Our contract assets were $44.3 million and $26.1 million as of December 31, 2018 and January 1, 2018, respectively. The current and long-term portions of our contract asset balance at December 31, 2018 are included within other current assets and other assets, net, respectively, in our consolidated balance sheet. We record deferred revenue when we receive payment prior to transferring goods or services to a customer. We primarily defer revenue for (i) installation and other upfront services and (ii) other services that are invoiced prior to when services are provided. Our deferred revenue balances were $877.9 million and $999.5 million as of December 31, 2018 and January 1, 2018, respectively. The decrease in deferred revenue during 2018 is primarily due to $901.4 million of revenue recognized that was included in our deferred revenue balance at January 1, 2018, partially offset by advanced billings in certain markets. The current and long-term portions of our deferred revenue balance at December 31, 2018 are included within deferred revenue and other long-term liabilities, respectively, in our consolidated balance sheet. Contract Costs Our aggregate assets associated with incremental costs to obtain and fulfill our contracts were $73.0 million and $68.1 million at December 31, 2018 and January 1, 2018, respectively. The current and long-term portions of our assets related to contract costs at December 31, 2018 are included within other current assets and other assets, net, respectively, in our consolidated balance sheet. We amortized $99.8 million to operating costs and expenses during 2018 related to these assets. Unsatisfied Performance Obligations A large portion of our revenue is derived from customers who are not subject to contracts. Revenue from customers who are subject to contracts is generally recognized over the term of such contracts, which is typically 12 months for our residential service contracts, one to three years for our mobile service contracts and one to five years for our B2B service contracts.

If we transfer goods or services to a customer but do not have an unconditional right to payment, we record a contract asset. Contract assets typically arise from the uniform recognition of introductory promotional discounts over the contract period and accrued revenue for handset sales. Our contract assets were $44.3 million and $26.1 million as of December 31, 2018 and January 1, 2018, respectively. The current and long-term portions of our contract asset balance at December 31, 2018 are included within other current assets and other assets, net, respectively, in our consolidated balance sheet.

We record deferred revenue when we receive payment prior to transferring goods or services to a customer. We primarily defer revenue for (i) installation and other upfront services and (ii) other services that are invoiced prior to when services are provided. Our deferred revenue balances were $877.9 million and $999.5 million as of December 31, 2018 and January 1, 2018, respectively. The decrease in deferred revenue during 2018 is primarily due to $901.4 million of revenue recognized that was included in our deferred revenue balance at January 1, 2018, partially offset by advanced billings in certain markets. The current and long-term portions of our deferred revenue balance at December 31, 2018 are included within deferred revenue and other long-term liabilities, respectively, in our consolidated balance sheet.

Our aggregate assets associated with incremental costs to obtain and fulfill our contracts were $73.0 million and $68.1 million at December 31, 2018 and January 1, 2018, respectively. The current and long-term portions of our assets related to contract costs at December 31, 2018 are included within other current assets and other assets, net, respectively, in our consolidated balance sheet. We amortized $99.8 million to operating costs and expenses during 2018 related to these assets.