Commitments and Contingencies - Colombia-Related Matters - Insurance Recovery (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended		1 Months Ended		3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2013 Colombia Insurance recovery coverage suit insurer	Sep. 30, 2014 Colombia Insurance recovery coverage suit	Dec. 31, 2008 Colombia Insurance recovery coverage suit insurer	Dec. 31, 2009 Colombia Insurance recovery coverage suit insurer	Jun. 30, 2013 Colombia Two insurers who had been placed in liquidation insurer	Dec. 31, 2009 Colombia Two insurers who had been placed in liquidation	Sep. 30, 2014 Colombia Defendant seeking a declaratory judgment relieving coverage obligation insurer	Dec. 31, 2009 Colombia Defendant seeking a declaratory judgment relieving coverage obligation
Gain Contingencies [Line Items]
Initial number of primary general liability insurers involved in coverage suit					1		3		2		1
Number of primary insurers with which the company reached settlement agreements								3
Percent of defense costs in the ATA and ATS lawsuits to be paid by primary insurers								40.00%		1.00%		40.00%
Expense reimbursement received to date which is deferred in Other liabilities						$ 12,000,000
Interest income	$ 600,000	$ 690,000	$ 1,905,000	$ 2,197,000		$ 1,000,000