Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Total assets measured at fair value	$ 1,119	$ 0
Liabilities:
Total liabilities measured at fair value	165,204	206,270
Derivative
Assets:
Derivative assets	1,119	0
Contingent consideration
Liabilities:
Total liabilities measured at fair value	15,694	19,112
Deferred consideration
Liabilities:
Total liabilities measured at fair value	149,510	187,158
Level 1
Assets:
Total assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	0	0
Level 1 | Derivative
Assets:
Derivative assets	0	0
Level 1 | Contingent consideration
Liabilities:
Total liabilities measured at fair value	0	0
Level 1 | Deferred consideration
Liabilities:
Total liabilities measured at fair value	0	0
Level 2
Assets:
Total assets measured at fair value	1,119	0
Liabilities:
Total liabilities measured at fair value	149,510	187,158
Level 2 | Derivative
Assets:
Derivative assets	1,119	0
Level 2 | Contingent consideration
Liabilities:
Total liabilities measured at fair value	0	0
Level 2 | Deferred consideration
Liabilities:
Total liabilities measured at fair value	149,510	187,158
Level 3
Assets:
Total assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	15,694	19,112
Level 3 | Derivative
Assets:
Derivative assets	0	0
Level 3 | Contingent consideration
Liabilities:
Total liabilities measured at fair value	15,694	19,112
Level 3 | Deferred consideration
Liabilities:
Total liabilities measured at fair value	$ 0	$ 0