Segment information Segment information narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Major Customers Percentage Of Total Revenues Minimum	10.00%
United States [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	1,300	$ 883
Ireland [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	127	118
Canada [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	86	$ 55