Acquisitions (Schedule of Consideration Paid And Net Assets Acquired, Business Acquisitions) (Details) (USD $)			9 Months Ended		0 Months Ended				0 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Earn-Out Arrangements [Member]	Sep. 30, 2013 Earn-Out Arrangements [Member]	Jun. 01, 2014 Pacer [Member]	Jun. 01, 2014 Pacer [Member]	Jun. 01, 2014 Pacer [Member] Pre-Qualifications [Member]	Jun. 01, 2014 Pacer [Member] Equity Method Investments [Member]	Jun. 01, 2014 Pacer [Member] Earn-Out Arrangements [Member]
Acquisition consideration:
Cash					$ 126,500,000
Fair value of contingent consideration (earn-out liability)			34,988,000	29,971,000					25,700,000
Total consideration transferred					152,200,000
Identifiable assets acquired and liabilities assumed:
Current assets						118,400,000
Equity method investments								2,300,000
Other long-term assets						100,000
Property and equipment						72,800,000
Pre-qualifications							41,200,000
Finite-lived intangible assets						20,300,000
Current liabilities						(55,800,000)
Long-term debt						(87,000,000)
Deferred income taxes						(29,600,000)
Total identifiable net assets						82,700,000
Goodwill	1,000,024,000	902,044,000				69,500,000
Total net assets acquired, including goodwill						$ 152,200,000