Stockholders' Equity - Private Placement (Details) € / shares in Units, $ / shares in Units, $ in Thousands, € in Millions	1 Months Ended		12 Months Ended
	Apr. 30, 2015 EUR (€) € / shares shares	Apr. 30, 2015 USD ($) shares	Dec. 31, 2015 USD ($)	Sep. 30, 2015 shares	Apr. 30, 2015 USD ($) $ / shares
Stockholders' Equity
Proceeds from April 2015 financing | $			$ 44,836
April 2015 Financing
Stockholders' Equity
Proceeds from April 2015 financing	€ 42.1	$ 44,800
Aggregate purchase price of shares to be sold in the second tranche | $					$ 70,000
Proceeds from April 2015 financing and the related conversion of outstanding convertible loan agreements and silent partnership interests | $		$ 77,300
Number of shares issued for each preferred dividend right				17,149
Preferential right to acquire additional shares (in dollars per share) | € / shares	€ 1.00
April 2015 Financing | Common Stock
Stockholders' Equity
Number of shares sold	730,162	730,162
Number of shares issued for cash consideration	511,188	511,188
Shares issued price per share | (per share)	€ 82.35				$ 87.71
Shares issued in exchange for the conversion of convertible loans and silent partnerships investments	218,974	218,974