Long-Term Debt (Schedule of Deferred Financing Costs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			1 Months Ended	3 Months Ended									1 Months Ended				3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 28, 2013 Term Loan [Member]	Jun. 30, 2013 Term Loan [Member]	Dec. 31, 2012 Term Loan [Member]		Dec. 31, 2012 Revolving Credit Facility [Member]		Dec. 31, 2013 Term Loan Maturing June 2018 [Member]		Dec. 31, 2013 Revolving Credit Facility Maturing June 2018 [Member]		Mar. 31, 2012 2025 Notes [Member]	Dec. 31, 2012 2025 Notes [Member]	Dec. 31, 2013 2032 Notes [Member]	Dec. 31, 2012 2032 Notes [Member]	Mar. 31, 2012 Senior Unsecured Notes [Member]	Dec. 31, 2013 Senior Unsecured Notes [Member]	Dec. 31, 2011 Senior Unsecured Notes [Member]	Dec. 31, 2012 Senior Unsecured Notes [Member]		Dec. 31, 2013 MARAD Debt [Member]	Dec. 31, 2012 MARAD Debt [Member]
Gross Carrying Amount	$ 32,872	$ 70,622				$ 15,318	[1]	$ 20,021	[1]	$ 3,638	[2]	$ 13,275	[2]		$ 8,189	$ 3,759	$ 4,251				$ 10,643	[3]	$ 12,200	$ 12,200
Accumulated Amortization	(8,575)	(46,284)				(11,595)	[1]	(12,466)	[1]	(364)	[2]	(1,327)	[2]		(8,189)	(1,148)	(534)				(8,252)	[3]	(5,736)	(5,248)
Net	24,297	24,338				3,723	[1]	7,555	[1]	3,274	[2]	11,948	[2]			2,611	3,717				2,391	[3]	6,464	6,952
Amortization of deferred financing costs	$ 5,187	$ 9,086	$ 8,910	$ 2,900	$ 600									$ 300				$ 2,000	$ 2,100	$ 900

[1] Relates to the term loans and revolving credit facility under our former credit agreement, which was terminated in June 2013.

[2] Relates to amounts allocated to the existing Term Loan and Revolving Credit Facility, which became effective in June 2013.

[3] In July 2013, we redeemed our remaining Senior Unsecured Notes. In connection with this redemption, we recorded a charge of $2.1 million to accelerate the remaining deferred financing costs associated with the original issuance of this debt.