Stock-Based Compensation - RSUs Outstanding (Details) - $ / shares shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair value assumptions
Dividends distributed on the company's Common Stock (in dollars per share)	$ 0.21	$ 0.21	$ 0.21	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.18	$ 0.82	$ 0.75	$ 0.71
Class A
Fair value assumptions
Dividends distributed on the company's Common Stock (in dollars per share)									0.82	0.75	0.71
Class B
Fair value assumptions
Dividends distributed on the company's Common Stock (in dollars per share)									$ 0.82	$ 0.75	$ 0.71
Management Stock Purchase Plan | Restricted stock units (RSUs)
RSUs Outstanding
Number Outstanding (in shares)	154				174				154	174	148	101
Weighted Average Purchase Price (in dollars per share)	$ 45.02				$ 39.68				$ 45.02	$ 39.68	$ 36.37	$ 36.14
RSUs Vested
Number Vested (in shares)	66				57				66	57	28
Weighted Average Purchase Price (in dollars per share)	$ 38.17				$ 36.26				$ 38.17	$ 36.26	$ 37.78
Fair value assumptions
Expected life (years)									3 years	3 years	3 years
Expected stock price volatility (as a percent)									24.10%	25.00%	24.80%
Expected dividend yield (as a percent)									1.00%	1.20%	1.30%
Risk-free interest rate (as a percent)									2.40%	1.50%	0.90%
Weighted average grant-date fair value (in dollars per share)									$ 21.80	$ 16.84	$ 18.15
$35.41-$40.27 | Management Stock Purchase Plan | Restricted stock units (RSUs)
Information about RSUs outstanding
Low end of purchase price range (in dollars per share)									35.41
High end of purchase price range (in dollars per share)									$ 40.27
RSUs Outstanding
Number Outstanding (in shares)	80								80
Weighted Average Purchase Price (in dollars per share)	$ 35.47								$ 35.47
RSUs Vested
Number Vested (in shares)	54								54
Weighted Average Purchase Price (in dollars per share)	$ 35.50								$ 35.50
$49.92-$61.84 | Management Stock Purchase Plan | Restricted stock units (RSUs)
Information about RSUs outstanding
Low end of purchase price range (in dollars per share)									49.92
High end of purchase price range (in dollars per share)									$ 61.84
RSUs Outstanding
Number Outstanding (in shares)	74								74
Weighted Average Purchase Price (in dollars per share)	$ 55.37								$ 55.37
RSUs Vested
Number Vested (in shares)	12								12
Weighted Average Purchase Price (in dollars per share)	$ 49.92								$ 49.92