Consolidated 50% Owned Subsidiaries, including Variable Interest Entities ("VIE") - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Noncontrolling Interest [Line Items]
Members’ interest subject to mandatory redemption	$ 40,000		$ 40,000		$ 40,000
Total disability insurance policies, per policy amount	20,000		20,000
Net accumulated earnings	5,100	$ 4,500	10,400	$ 7,000
Variable Interest Entity, Primary Beneficiary
Noncontrolling Interest [Line Items]
Members’ interest subject to mandatory redemption	40,000		40,000
Myers \| Variable Interest Entity, Primary Beneficiary
Noncontrolling Interest [Line Items]
Members’ interest subject to mandatory redemption	$ 20,000		$ 20,000