Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Summary of Financial Instruments at Carrying and Fair Value) (Details)

v3.7.0.1
Fair Value Measurements (Summary of Financial Instruments at Carrying and Fair Value) (Details) - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Carrying Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total $ 390,536 $ 390,219
Fair Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total 416,000 412,000
6.125% senior unsecured notes due 2024 [Member] | Carrying Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
6.125% Senior Notes [1] 390,536 390,219
6.125% senior unsecured notes due 2024 [Member] | Fair Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
6.125% Senior Notes [1] $ 416,000 $ 412,000
[1] The fair value was based upon Level 2 inputs. See Note 4 for additional information about the Company's 6.125% Senior Notes.