Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair value inputs, Level 2 [Member]
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	$ 296,582	$ 292,065
Interest Rate Swap [Member] | Fair value inputs, Level 2 [Member]
Debt Instrument [Line Items]
Assets, Fair Value Disclosure	134	1,019
Financial Liabilities Fair Value Disclosure	707	1,065
6.5% Senior Notes [Member] | Fair value inputs, Level 2 [Member]
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	295,875	291,000
Carrying Amount [Member]
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	297,612	297,644
Carrying Amount [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Assets, Fair Value Disclosure	134	1,019
Financial Liabilities Fair Value Disclosure	707	1,065
Carrying Amount [Member] | 6.5% Senior Notes [Member]
Debt Instrument [Line Items]
Financial Liabilities Fair Value Disclosure	$ 296,905	$ 296,579