Fair Value Measurements (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term Debt gross	$ 638,112	$ 458,763
Fair Value, Liabilities Measured on Recurring Basis, Gain (Loss) Included in Other Income	356,000
Contingent Consideration Discount Rate Used	1.60%
Minimum [Member]
Statement [Line Items]
Estimated Probability Of Fair Value Variables Range	25.00%
Maximum [Member]
Statement [Line Items]
Estimated Probability Of Fair Value Variables Range	40.00%
Fixed Interest Rate [Member]
Debt Instrument [Line Items]
Long-term Debt gross	354,105,000	101,188,000
Long-term Debt, Fair Value	379,036,000	105,302,000
Variable Interest Rate [Member]
Debt Instrument [Line Items]
Long-term Debt gross	284,007,000	357,575,000
Long-term Debt, Fair Value	$ 284,007,000	$ 357,575,000