Other Assets, Net
12 Months Ended
Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]  
Other Assets, Net
9.
Other Assets, Net
 
As of December 31,
 
2016
 
2015
Deferred debt issuance costs, net
$
12,121

 
$
14,198

Natural gas transportation, long-term portion
445

 
368

Other
1,102

 
1,594

Other assets, net
$
13,668

 
$
16,160


Deferred Debt Issuance Costs
The Partnership recorded amortization expense related to deferred debt issuance costs of $4.0 million, $3.6 million and $4.8 million during the years ended December 31, 2016, 2015 and 2014, respectively. Deferred debt issuance costs are amortized over the life of the related debt on a straight-line basis and recorded in interest expense.
Natural Gas Transportation Assets
The Partnership records the fair value of natural gas transportation contracts acquired in business combinations. In 2016, the Partnership recorded an asset of $8.0 million and a liability of $2.4 million in connection with the SBE acquisition. In 2014, the Partnership recorded an asset of $39.4 million and a liability of $1.5 million in connection with the Metromedia Energy acquisition.
These assets and liabilities are being amortized into cost of products sold (exclusive of depreciation and amortization) in the natural gas segment over the life of the underlying agreements. During the year ended December 31, 2016, 2015 and 2014, the Partnership recorded a charge to cost of products sold (exclusive of depreciation and amortization) of $6.5 million, $13.4 million and $21.9 million, respectively, which included $1.6 million, $3.6 million and $13.6 million, respectively, due to a decline in value as a result of decreasing natural gas spreads.
The estimated future expense of the net natural gas transportation assets for the years ended December 31, 2017 and 2018 is $1.7 million and $0.1 million, respectively. The amount expected to be expensed in the year ended December 31, 2017 has been recorded in other current assets and other current liabilities.