Fair Value Measurements - Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Total	$ 135,204	$ 122,818
Liabilities:
Subsidiary unit awards	2,768	532
Contingent consideration liability from acquisition	0	230
Total	2,768	762
Money market account
Assets:
Money market account	135,204	122,818
Level 1
Assets:
Total	135,204	122,818
Liabilities:
Subsidiary unit awards	0	0
Contingent consideration liability from acquisition	0	0
Total	0	0
Level 1 | Money market account
Assets:
Money market account	135,204	122,818
Level 2
Assets:
Total	0	0
Liabilities:
Subsidiary unit awards	0	0
Contingent consideration liability from acquisition	0	0
Total	0	0
Level 2 | Money market account
Assets:
Money market account	0	0
Level 3
Assets:
Total	0	0
Liabilities:
Subsidiary unit awards	2,768	532
Contingent consideration liability from acquisition	0	230
Total	2,768	762
Level 3 | Money market account
Assets:
Money market account	$ 0	$ 0