Fair Value of Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities, fair value	$ 1,829	$ 785
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities, fair value	1,725	765
Level 2 [Member] | Secured Notes One [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes	0	120,000
Level 2 [Member] | Secured Notes Two [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes	0	20,000
Borrowings [Member] | Unsecured debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities, fair value	380,059	180,000
Borrowings [Member] | Unsecured debt [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unsecured notes	375,000	180,000
Liabilities, fair value	$ 380,059	$ 180,000