Employee Benefit Plans (Details) - Profit Sharing Plan - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Contribution Plan Disclosure [Line Items]
Profit sharing expense		$ 33,309	$ 31,852	$ 27,245
Profit Sharing Expense
Defined Contribution Plan Disclosure [Line Items]
Profit sharing expense	[1]	6,171	6,919	6,354
Company dividends received by the Profit Sharing Plan		$ 494	$ 466	$ 428
Company shares held by the Profit Sharing Plan at the end of the year:
Number of shares		1,175,858	1,277,567	1,364,558
Fair value		$ 29,667	$ 23,546	$ 23,348

[1] Included in retirement and other employee benefits in the Consolidated Statements of Income