Short-Term Borrowing Short-Term Borrowing - Schedule of Short-Term Debt (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 320,000
Long-term Line of Credit		201,311	$ 168,757
Line of Credit Facility, Remaining Borrowing Capacity		118,689
Bank Overdrafts	[1]	8,560	4,640
Short-term borrowing		209,871	173,397
Committed Line of Credit Facility One [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 55,000
Line of Credit Facility, Expiration Date		Oct. 29, 2017
Long-term Line of Credit		$ 45,000	30,000
Line of Credit Facility, Remaining Borrowing Capacity		$ 10,000
Debt Instrument, Description of Variable Rate Basis		LIBOR rate, plus 1.00 percent
Short-term Revolving Line of Credit Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 50,000
Line of Credit Facility, Expiration Date		Oct. 31, 2017
Long-term Line of Credit		$ 50,000	50,000
Debt Instrument, Description of Variable Rate Basis		Lender's base rate plus 80 basis points
Committed Line of Credit Facility Three [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 35,000
Line of Credit Facility, Expiration Date		Dec. 19, 2017
Long-term Line of Credit		$ 35,000	30,000
Line of Credit Facility, Remaining Borrowing Capacity		$ 0
Debt Instrument, Description of Variable Rate Basis		Lender's base rate, plus 0.85 percent
Committed Line of Credit Facility Four [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 150,000
Line of Credit Facility, Expiration Date		Oct. 08, 2020
Long-term Line of Credit		$ 50,000	35,000
Line of Credit Facility, Remaining Borrowing Capacity		$ 100,000
Debt Instrument, Description of Variable Rate Basis		LIBOR rate, plus 1.00 percent
Committed Line of Credit Facility Two [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 30,000
Line of Credit Facility, Expiration Date		Oct. 31, 2017
Long-term Line of Credit		$ 21,311	$ 23,757
Line of Credit Facility, Remaining Borrowing Capacity		$ 8,689
Debt Instrument, Description of Variable Rate Basis		LIBOR rate, plus 1.00 percent

[1] If presented, these book overdrafts would be funded through the bank revolving credit facilities.