Segments Information - Segment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segments Information
Total segment income	$ 112,116	$ 87,741	$ 318,623	$ 247,133
Selling, general, and administrative expense	(236,174)	(186,255)	(640,108)	(536,966)
Depreciation and amortization	(8,382)	(6,219)	(22,819)	(18,144)
Other interest expense, net	(11,012)	(12,715)	(30,973)	(38,040)
Other expense, net	(96)		(79)	(2)
Income before income taxes	93,594	70,704	268,268	194,240
Operating Segments
Segments Information
Total segment income	115,121	90,729	328,600	252,846
Depreciation and amortization	(8,154)	(6,219)	(22,476)	(18,144)
Other interest expense, net	(1,424)	(1,486)	(4,380)	(4,262)
Corporate, Non-Segment
Segments Information
Selling, general, and administrative expense	(2,037)	(1,091)	(6,461)	(2,420)
Depreciation and amortization	(228)		(343)
Other interest expense, net	(9,588)	(11,229)	(26,593)	(33,778)
Consumer services and plans | Operating Segments
Segments Information
Total segment income	21,675	19,847	71,887	63,948
Depreciation and amortization	(888)	(926)	(2,889)	(2,777)
Other interest expense, net	(1)	(4)	(5)	(12)
Retail | Operating Segments
Segments Information
Total segment income	93,446	70,882	256,713	188,898
Depreciation and amortization	(7,266)	(5,293)	(19,587)	(15,367)
Other interest expense, net	$ (1,423)	$ (1,482)	$ (4,375)	$ (4,250)