Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transactions
Total revenues	$ 852,446	$ 1,100,844	$ 1,199,004
Receivables due from the Funds	21,600	26,700
Investment management fees
Related Party Transactions
Total revenues	523,304	654,727	709,179
Rule 12b-1 service and distribution fees
Related Party Transactions
Total revenues	208,901	303,046	338,846
Shareholder service fees
Related Party Transactions
Total revenues	$ 120,241	$ 143,071	$ 150,979