Preferred Shares Preferred Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 16, 2017	Apr. 10, 2013	Mar. 15, 2007
Preferred Shares [Abstract]
Preferred Stock, Shares Authorized		2,000,000	2,000,000		2,000,000	2,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01
Shares, Issued							4,000,000
Preferred Stock, Dividend Rate, Percentage		9.75%
Preferred Stock, Shares Issued		0	2,000				4,000
Preferred shares redeemed					2,000	2,000
Payments for Repurchase of Redeemable Preferred Stock	$ 50,352	$ 50,420
Preferred Stock, Redemption Price Per Share		$ 609.375
Preferred dividends		$ 3,656	$ 4,875	$ 4,875