Stockholders' Equity - Reconciliation of Beginning and End of Period Equity Accounts (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,232,443	$ 1,185,756
Net income	7,178	8,983
Other comprehensive loss	14,149	30,521
Share repurchase program		(15,565)
Stock compensation plans	(290)	(335)
Cash dividends	(5,262)	(5,334)
Ending Balance	$ 1,248,218	$ 1,204,026
Dividends paid (in dollars per share)	$ 0.105	$ 0.105
Total Parent Stockholders’ Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,172,043	$ 1,127,096
Net income	6,979	8,285
Other comprehensive loss	13,170	26,576
Share repurchase program		(15,565)
Stock compensation plans	(290)	(335)
Cash dividends	(5,262)	(5,334)
Ending Balance	1,186,640	1,140,723
Noncontrolling Shareholders’ Interests in Consolidated Subsidiaries
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	60,400	58,660
Net income	199	698
Other comprehensive loss	979	3,945
Ending Balance	$ 61,578	$ 63,303