Performance-Based Common Stock Warrants - Purchase Level and Number of Warrants to Vest (Details) - Common Stock Purchase Warrants - Supply Threshold	Mar. 09, 2016 USD ($) shares
Class of Warrant or Right [Line Items]
Aggregate level of purchases, threshold one | $	$ 260,000,000
Aggregate level of purchases, threshold two | $	300,000,000
Aggregate level of purchases, threshold three | $	$ 340,000,000
Incremental Warrants That Will Vest January 1, 2016 - December 31, 2017
$260 million threshold (in shares)	100,000
$300 million threshold (in shares)	75,000
$340 million threshold (in shares)	75,000
Maximum Potential Warrants Earned by Comcast (in shares)	250,000
Incremental Warrants That Will Vest January 1, 2018 - December 31, 2019
$260 million threshold (in shares)	100,000
$300 million threshold (in shares)	75,000
$340 million threshold (in shares)	75,000
Maximum Potential Warrants Earned by Comcast (in shares)	250,000
Incremental Warrants That Will Vest January 1, 2020 - December 31, 2021
$260 million threshold (in shares)	75,000
$300 million threshold (in shares)	75,000
$340 million threshold (in shares)	75,000
Maximum Potential Warrants Earned by Comcast (in shares)	225,000