Stockholder's Equity Stockholder's Equity Additional Information (Details)		9 Months Ended			12 Months Ended
		Sep. 30, 2017 USD ($) $ / shares $ / right $ / unit shares		Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares
Equity [Abstract]
Preferred Stock, Shares Authorized | shares		2,000,000			2,000,000
Preferred Stock, Par or Stated Value Per Share | $ / shares		$ 0.01			$ 0.01
Stock Issued During Period, Shares, New Issues | shares		960,488			960,488.00
Stock Issued During Period, Value, Other		$ 62.26			$ 62.26
Proceeds from issuance of common stocks	[1]				57,360,000
Proceeds from Issuance of Common Stock		$ (10,000)	[1]	$ 57,306,000	$ 57,360,000	[1]
Common Stock ownership percentage		15.00%
Preferred stock price per unit | $ / unit		70
redemption price per right | $ / right		0.01

[1] On September 22, 2016, we completed a public offering of 960,488 shares of our common stock at a price per share of $62.26. The net proceeds from the sale of common stock, after deducting underwriting commissions and expenses, were approximately $57.4 million.