Share-Based Compensation (Changes In Share Options Awards) (Details) (GBP £) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Outstanding at the beginning of the year Weighted Average Exercise Price	£ 7.32	£ 7.31	£ 7.85
Forfeited during the period Weighted Average Exercise Price	£ 0.00	£ 0.00	£ 14.80
Exercised during the period Weighted Average Exercise Price	£ 6.83	£ 7.30	£ 8.08
Outstanding at the end of the year Weighted Average Exercise Price	£ 8.86	£ 7.32	£ 7.31
Exercisable at the end of the period Weighted Average Exercise Price	£ 8.86	£ 7.32	£ 7.31
Stock Options [Member]
Outstanding at the beginning of the year	1.1	2.6	4.5
Forfeited during the period	0	0	(0.2)
Exercised during the year	(0.9)	(1.5)	(1.7)
Outstanding at the end of the year	0.2	1.1	2.6
Exercisable at the end of the period	0.2	1.1	2.6