Stockholders' Equity (Details) $ / shares in Units, $ in Thousands	1 Months Ended		9 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares	Jan. 31, 2017 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) Vote $ / shares	Sep. 30, 2016 USD ($)
Stockholders’ Equity
Common stock, shares issued | shares	3,920,454	5,750,000
Sale of stock, price per share | $ / shares	$ 88.00	$ 41.00	$ 88.00
Proceeds from the sale of common stock, net of issuance costs | $	$ 324,600	$ 221,200	$ 545,838	$ 0
Number Of Vote Per Common Stock | Vote			1