FINANCIAL INSTRUMENTS NAV Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Private equity funds measured at net asset value (1)	[1]	$ 13,689	$ 12,658
Percentage of funds that have investment restrictions		100.00%
Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded commitments relating to private equity funds		$ 7,200	9,200
Estimate of Fair Value Measurement [Member] | Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Private equity funds measured at net asset value (1)		$ 13,700	$ 12,700

[1] Investments measured at fair value using the net asset value practical expedient have not been classified in the fair value hierarchy. The fair value amounts are presented in the above table to facilitate reconciliation to the condensed consolidated balance sheets.