Acquisitions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Significant Acquisitions and Disposals [Line Items]
Other Cost and Expense, Operating	$ 113,694	$ 3,999	$ 11,284	$ 10,276	$ 2,896	$ 61,632	$ 31,268	$ 4,006	$ 139,253	$ 99,802	$ 65,713
Payments to Acquire Businesses, Net of Cash Acquired									1,613	3,895	34,873
Acquisition And Other Related Costs [Member]
Significant Acquisitions and Disposals [Line Items]
Other Cost and Expense, Operating									$ 0	$ 2,300	$ 1,380