Fixed Assets and Asset Retirement Obligations (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fixed Assets And Asset Retirement Obligations [Abstract]
Amortization of Intangible Assets	$ 14,560	$ 19,930	$ 30,900
Depreciation expense	$ 46,336	$ 37,398	$ 27,500