Stockholders' Equity (Details Textual) - USD ($) $ in Thousands						9 Months Ended		12 Months Ended	51 Months Ended
	Jan. 01, 2018	Jan. 01, 2017	Jan. 01, 2016	Jun. 30, 2015	Nov. 14, 2013	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2013	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)						0
Capital shares reserved for future issuance, annual increase, maximum	1,125,846	1,072,870	1,042,766
Exercises in period, intrinsic value						$ 38,639
Restricted Stock Units and Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Antidilutive securities excluded from computation of Earnings Per Share, amount						3,354,028	3,775,137
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized						$ 397
Compensation cost not yet recognized, period for recognition						214 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized						$ 84,994
Compensation cost not yet recognized, period for recognition						978 days
The 2005 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance								4,713,319
Vesting period (in years)								4 years
Granted (in shares)									0
Shares available for grant						0
The 2013 Omnibus Equity Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance					1,904,633
Percentage of outstanding stock reserved for grant					4.00%
Percentage of outstanding stock maximum					5.00%
The 2013 Omnibus Equity Award Plan | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)					4 years
2015 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum employee subscription rate				15.00%
Purchase price of common stock, percent				85.00%
Percent of shares increase, employee stock purchase plan				1.00%
Number of shares authorized				500,000
Common stock availability threshold, Employee Stock Purchase Plan				2.00%
Shares increase threshold, employee stock purchase plan				400,000
Number of additional shares authorized	188,813	158,695	21,383