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.