Summary of Significant Accounting Policies (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Changes in deferred financing costs
Balance at the beginning of the period	$ 3,402	$ 953	$ 3,311
Write-off of unamortized capitalized deferred financing costs		(335)	(2,045)
Deferred financing costs capitalized on new debt	168	3,471	559
Amortization of deferred financing costs	(776)	(687)	(872)
Balance at the end of the period	2,794	3,402	953
Loss on extinguishment of debt		673	7,967
Payment of call premium and post payoff interest on senior notes redemption			3,876
Revolving credit facility
Changes in deferred financing costs
Deferred financing costs capitalized on new debt	168
Prior senior credit facilities | Term loan facility
Changes in deferred financing costs
Write-off of unamortized capitalized deferred financing costs		(335)	(995)
Expenditure related to financing costs paid to existing lenders			2,045
Prior senior credit facilities | Senior notes
Changes in deferred financing costs
Write-off of unamortized capitalized deferred financing costs			(1,050)
Payment of call premium and post payoff interest on senior notes redemption			$ 3,876