Stockholders' Equity - Summary of activity under stock-based incentive plans (Details) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	May. 31, 2015
Stock Incentive Plan [Member]
Summary of the activity under the incentive plans
Stock-based awards, beginning of period (shares)	1,103,379	1,837,855	1,057,732	1,788,168	1,788,168
Granted (shares)	520	0	112,789	128,199
Vested (shares)	(520)	(4,911)	(67,142)	(83,423)
Forfeited (shares)	0	(67,798)			0	(67,798)
Stock-based awards, end of period (shares)	1,103,379	1,765,146	1,103,379	1,765,146	1,057,732	1,788,168
Stock Incentive Plan [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld to pay estimated withholding taxes			10,119	16,170
Common Stock [Member] | 2015 Employees Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance under the Plan							3,500,000