Share Based Compensation - Weighted Average and Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average estimated fair value	$ 13.86	$ 18.16	$ 18.12
Quarterly dividend rate	$ 0.40	$ 0.38	$ 0.33
Expected term of stock appreciation rights, in years	4 years 8 months	4 years 8 months	4 years 4 months 24 days
Risk-free interest rate	1.40%	1.20%	1.30%
Dividend yield	4.10%	2.60%	2.30%
Expected stock price volatility	29.40%	29.20%	30.30%
Present value of dividends	$ 7.27	$ 6.90	$ 5.76