Fair Value, Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Beginning of period balance	$ 25,218	$ 16,793
Total gains or losses (realized or unrealized) included in income	261	(175)
Purchases	1,069	0
Settlements	(5,602)	(316)
Transfers into Level 3	113	0
Transfers out of Level 3	(608)	0
End of period balance	$ 20,451	$ 16,302