Fair Value of Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities fair value		$ 320,785	$ 301,785
Other liabilities		229,335	199,187
Unsecured Debt [Member] | Borrowings [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities fair value		180,000	150,000
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities fair value		320,765	301,525
Level 2 [Member] | Unsecured Debt [Member] | Borrowings [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities fair value	[1]	180,000	150,000
Level 2 [Member] | Secured Notes One [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured loan		120,000	120,000
Level 2 [Member] | Secured Notes Two [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured loan		20,000	20,000
Options Sold [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities fair value		$ 20	260
Other liabilities			$ 260

[1] On July 2, 2013, the Company entered into an unsecured $200 million five-year revolving credit facility, which later was expanded to a borrowing capacity of $250 million. The interest rate on borrowings under the credit facility is based on the Company's debt to total capital ratio and ranges from LIBOR plus 112.5 basis points when the ratio is under 15% to LIBOR plus 162.5 basis points when the ratio is above 25%. Commitment fees for the undrawn portions of the credit facility range from 12.5 basis points when the ratio is under 15% to 22.5 basis points when the ratio is above 25%. Debt to capital ratio is expressed as a percentage of (a) consolidated debt to (b) consolidated shareholders' equity plus consolidated debt. In 2016, the interest rate was LIBOR plus 112.5 basis points on the $180 million of borrowings and 12.5 basis points on the undrawn portion of the credit facility. The interest rate was approximately 1.73% at December 31, 2016.