Stock-Based Compensation, Employee Stock Purchase Plan (Details) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended		12 Months Ended
	Jan. 31, 2019	Jul. 31, 2018	Dec. 31, 2018	May 03, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee discount on the purchase of common stock			5.00%
2008 Long Term Performance Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance under the amendment (in shares)				26.0
2009 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of fair market value for offering period			95.00%
Offering period to purchase shares			6 months
Share purchases funded through payroll deductions, value			$ 21,250
Issued shares under the ESPP (in shares)		0.1
Average price of issued shares under the ESPP (in dollars per share)		$ 192.96
Number of shares authorized for issuance under the amendment (in shares)			3.3
2009 Employee Stock Purchase Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share purchases funded through payroll deductions, percentage			10.00%
2009 Employee Stock Purchase Plan [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued shares under the ESPP (in shares)	0.1
Average price of issued shares under the ESPP (in dollars per share)	$ 162.91