Debt Schedule of Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term Debt	$ 277,590	$ 45,200
Long-term Debt, net of deferred financing costs	276,867	44,347
Loan Agreement
Debt Instrument [Line Items]
Long-term Debt	177,590	34,200
Less unamortized deferred financing fees
Debt Instrument [Line Items]
Less unamortized deferred financing fees	723	853
Four Point Six Seven Percent Senior Unsecured Notes Due Twenty Twenty One [Member] | Less unamortized deferred financing fees
Debt Instrument [Line Items]
Long-term Debt	40,000	0
Interest rate	4.67%
Five Point Two Five Percent Senior Unsecured Notes Due Twenty Twenty Four [Member] | Less unamortized deferred financing fees
Debt Instrument [Line Items]
Long-term Debt	11,000	11,000
Interest rate	5.25%
Five Point Three Zero Percent Senior Unsecured Notes Due Twenty Twenty Four [Member] | Less unamortized deferred financing fees
Debt Instrument [Line Items]
Long-term Debt	29,000	0
Interest rate	5.30%
Five Point Four Five Percent Senior Unsecured Notes Due Twenty Twenty Six [Member] | Less unamortized deferred financing fees
Debt Instrument [Line Items]
Long-term Debt	$ 20,000	$ 0
Interest rate	5.45%