Shareholders' Equity (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Stock Repurchase Program [Abstract]
Stock repurchase program, shares authorized (in shares)	2,464,209
Stock repurchase program, authorized amount	$ 25,000
Repurchase of common shares amount paid	9,293
Repurchase of common shares	$ 6,487	$ 1,280
Class A [Member]
Stock Repurchase Program [Abstract]
Repurchase of common stock (in shares)	2,893
Class B [Member]
Stock Repurchase Program [Abstract]
Repurchase of common stock (in shares)	371,188
Rule 10b5-1 [Member]
Stock Repurchase Program [Abstract]
Stock repurchase program, authorized amount	$ 4,000