Stockholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		1 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	May 31, 2014	Feb. 25, 2011	Nov. 30, 2013
Convertible Preferred Stock and Stockholders' Equity
Warrant expense (reduction)	$ (147)	$ 2,388
Third Party Marketing Firm
Convertible Preferred Stock and Stockholders' Equity
Shares issued for exercise of warrants			959,676
Common Stock Purchase Warrants | Vulcan
Convertible Preferred Stock and Stockholders' Equity
Shares that may be purchased under warrant						666,666
Exercise price of warrants (in dollars per share)						$ 15.00
Common Stock Purchase Warrants | Service Provider
Convertible Preferred Stock and Stockholders' Equity
Maximum number of shares under warrant agreement				333,333
Exercise price of warrants (in dollars per share)				$ 12.81
Period of warrant				5 years
Warrant vesting period				4 years
Period of warrant from termination date of agreement				12 months
Warrant expense (reduction)	(200)
Number of shares under warrants that have been earned	33,333
Common Stock Purchase Warrants | Third Party Marketing Firm
Convertible Preferred Stock and Stockholders' Equity
Maximum number of shares under warrant agreement					1,433,333
Exercise price of warrants (in dollars per share)					$ 6.02
Number of shares exercised through a net settlement			1,433,333
Warrant expense (reduction)		1,900
Number of shares under warrants that have been earned		238,674
Common Stock Purchase Warrants | USAA
Convertible Preferred Stock and Stockholders' Equity
Warrant expense (reduction)	$ 28	$ 400
Number of shares under warrants that have been earned	2,666	139,503
Common Stock Purchase Warrants | USAA | Affinity Group Marketing Agreement
Convertible Preferred Stock and Stockholders' Equity
Shares that may be purchased under warrant				1,458,979
Number of warrant tranches				2
Common Stock Purchase Warrants | USAA | Affinity Group Marketing Agreement | Tranche One
Convertible Preferred Stock and Stockholders' Equity
Shares that may be purchased under warrant				392,313
Exercise price of warrants (in dollars per share)				$ 7.95
Common Stock Purchase Warrants | USAA | Affinity Group Marketing Agreement | Tranche Two
Convertible Preferred Stock and Stockholders' Equity
Shares that may be purchased under warrant				1,066,666
Exercise price of warrants (in dollars per share)				$ 15.00