Fair Value Measurements (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Liabilities:
Contingent purchase price	$ 89,610	$ 96,957
Fair Value, Measurements, Recurring [Member]
Assets:
Money market	56,097	6,030
Total assets at fair value	56,097	6,030
Liabilities:
Contingent purchase price	129,410	123,757
Total liabilities at fair value	129,410	123,757
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Assets:
Money market	56,097	6,030
Total assets at fair value	56,097	6,030
Liabilities:
Contingent purchase price	0	0
Total liabilities at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Money market	0	0
Total assets at fair value	0	0
Liabilities:
Contingent purchase price	0	0
Total liabilities at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Money market	0	0
Total assets at fair value	0	0
Liabilities:
Contingent purchase price	129,410	123,757
Total liabilities at fair value	$ 129,410	$ 123,757