Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Supplemental Cash Flow Information [Line Items]
Interest paid	$ 126,540	$ 99,871
Income taxes paid	7,400	2,645
Increase (decrease) in liabilities for purchases of property and equipment	$ 430	$ (5,134)