Other Assets, Net - Additional Information (Detail) - USD ($) $ in Thousands |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
Jan. 10, 2014 |
|
| Indefinite-lived Intangible Assets [Line Items] | ||||
| Amortization expense related to deferred debt issuance costs | $ 3,600 | $ 4,800 | $ 3,900 | |
| Cost of products sold of natural gas transportation assets | 3,188,924 | 4,755,031 | $ 4,554,188 | |
| Estimated future expense of net natural gas transportation assets for 2016 | 2,300 | |||
| Estimated future expense of net natural gas transportation assets for 2017 | 300 | |||
| Natural Gas [Member] | ||||
| Indefinite-lived Intangible Assets [Line Items] | ||||
| Cost of products sold of natural gas transportation assets | 13,400 | 21,900 | ||
| Provision for inventory write-down | $ 3,600 | $ 13,600 | ||
| Metromedia Energy [Member] | ||||
| Indefinite-lived Intangible Assets [Line Items] | ||||
| Fair value of natural gas transportation assets acquired | $ 39,400 | |||
| Fair value of natural gas transportation liabilities acquired | $ 1,500 | |||