Shareholders’ Equity (Narrative) (Details) $ / shares in Units, $ in Thousands	1 Months Ended													3 Months Ended	4 Months Ended	12 Months Ended
	Aug. 31, 2017 shares	Mar. 31, 2017 USD ($) $ / shares shares	Feb. 28, 2017 consultant shares	Jan. 31, 2017 shares	Dec. 31, 2016 USD ($) $ / shares shares	Sep. 30, 2016 shares	Jan. 31, 2016	Sep. 30, 2015 USD ($) $ / shares shares	Aug. 31, 2015 USD ($) shares	Apr. 30, 2015 shares	Feb. 28, 2015 shares	Dec. 31, 2014 party shares	Sep. 30, 2013 employee shares	Dec. 31, 2016 USD ($) $ / shares shares	Nov. 30, 2015 consultant shares	Dec. 31, 2017 USD ($) series $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Jul. 31, 2015 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized (in shares)																8,000,000
Preferred stock, par value (usd per share) | $ / shares																$ 0.0001
Weighted-average grant date fair values of stock options granted (in dollars per share) | $ / shares																$ 23.80	$ 15.33	$ 22.56
Unamortized share-based compensation expense | $																$ 96,000
Recognized weighted average period																3 years 3 months 20 days
Stock options exercised (in shares)																174,628	17,548	51,814
Intrinsic value of stock options exercised | $																$ 3,300	$ 100	$ 900
Warrants granted to purchase common stock (in shares)												51,000
Warrants issued, number of third party recipients (party) | party												2
Third party share-based compensation expense | $																600	200	1,100
Share-based compensation expense | $																21,795	$ 14,546	13,072
Stock issued during period, value | $																$ 117,480		$ 104,596
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued (in shares)									4,000
Number of shares of unvested stock awards (in shares)					542,680							1,279,007		542,680		0	542,680	1,072,899
Vested awards (in shares)																542,680	530,219	210,108
Stock issued during period, value | $									$ 100
Grant One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant vesting period												4 years
Chief Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of unvested stock awards (in shares)																			1,042,680
Accelerated shares (in shares)					500,000
Vested awards (in shares)																542,680
One-year Anniversary Date of Grant [Member] | Grant One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant vesting rights percentage												25.00%
One-year Anniversary Date of Grant [Member] | Grant Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant vesting rights percentage				100.00%			100.00%					100.00%
2013 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity plan, term													10 years
Period of share-based payment awards													4 years
Shares of common stock authorized for issuance (in shares)					4,600,000									4,600,000		8,100,000	4,600,000	3,100,000
Shares available for grant (in shares)																1,875,732
Shares of common stock for future issuance (in shares)																7,853,034
2013 Equity Plan [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards													1 year
2013 Equity Plan [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards	2 years		1 year								3 years
Award vesting rights, percentage			25.00%
Stock options granted (in shares)			42,000								60,000
Share-based compensation expense | $																$ 400		$ 400
Number of award recipients (consultant/employee) | consultant			3
Number of stock options (option)						2
Number of modified stock options (option)	2
2013 Equity Plan [Member] | Consultant [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)															50,000
Share-based compensation expense | $																	$ (100)	$ 100
Number of award recipients (consultant/employee) | consultant															2
Performance achievement percent														75.00%
Percentage of options canceled														25.00%
2013 Equity Plan [Member] | Chief Financial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)										60,000
2013 Equity Plan [Member] | One-year Anniversary Date of Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage													25.00%
2013 Equity Plan [Member] | One-year Anniversary Date of Grant [Member] | Chief Financial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage										25.00%
2013 Equity Plan [Member] | Share-based Compensation Award, Tranche One [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards			3 years
2013 Equity Plan [Member] | Share-based Compensation Award, Tranche One [Member] | Chief Financial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards										3 years
2013 Equity Plan [Member] | Share-based Compensation Award, Tranche Two [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards			2 years
2013 Equity Plan [Member] | Upon Grant [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage											25.00%
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued (in shares)																3,731,000		2,933,000
Stock options exercised (in shares)																175,000	17,000	45,000
Common Stock [Member] | Director [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued (in shares)													79,622
Common Stock [Member] | Chief Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued (in shares)													1,327,048
Common Stock [Member] | Employees [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued (in shares)													336,185
Number of award recipients (consultant/employee) | employee													3
Series C-1 Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized (in shares)					11,000									11,000		11,000	11,000
Preferred stock, par value (usd per share) | $ / shares					$ 0.0001									$ 0.0001		$ 0.0001	$ 0.0001
Shares issued upon conversion, per share (in shares)																		1,724
Preferred stock, shares issued (in shares)					3,906									3,906		3,906	3,906
Preferred stock, shares outstanding (in shares)					3,906									3,906		3,906	3,906
Shares reserved for future issuance (in shares)					6,735,378									6,735,378		6,735,378	6,735,378
Liquidation preference per share (in dollars per share) | $ / shares																$ 1,000
Liquidation preference | $					$ 3,906									$ 3,906		$ 3,906	$ 3,906
Series C-1 Convertible Preferred Stock [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued (in shares)																		19,134
Series F Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized (in shares)					10,000									10,000		10,000	10,000
Preferred stock, par value (usd per share) | $ / shares					$ 0.0001									$ 0.0001		$ 0.0001	$ 0.0001
Shares issued upon conversion, per share (in shares)																		286
Preferred stock, shares issued (in shares)					2,737									2,737		2,737	2,737
Preferred stock, shares outstanding (in shares)					2,737									2,737		2,737	2,737
Shares reserved for future issuance (in shares)					782,032									782,032		782,032	782,032
Liquidation preference per share (in dollars per share) | $ / shares																$ 1,000
Liquidation preference | $					$ 2,737									$ 2,737		$ 2,737	$ 2,737
Series F Preferred Stock [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued (in shares)																		17,360
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant granted to purchase common stock (in shares)				25,013	17,000									17,000			17,000
Common Stock [Member] | 2013 Equity Plan [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage						25.00%
Stock options granted (in shares)						35,000
Common Stock [Member] | 2013 Equity Plan [Member] | Share-based Compensation Award, Tranche One [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards						1 year
Common Stock [Member] | 2013 Equity Plan [Member] | Share-based Compensation Award, Tranche Two [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards						3 years
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of series (series) | series																1
Underwriting Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock to be issued and sold in underwriting agreement (in shares)		3,731,344						2,932,500
Price per share of shares sold (usd per share) | $ / shares		$ 33.50
Proceeds from the underwriting agreement, including additional shares sold, gross | $		$ 125,000						$ 111,400
Proceeds from the underwriting agreement, including additional shares sold, net of cost | $		117,500						104,600
Issuance costs | $		$ 7,500						$ 6,800
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price per share of shares sold (usd per share) | $ / shares								$ 38.00