Stock Compensation Plans Activity for the Company's restricted stock and restricted stock units (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning of period, shares	653,000	928,000	1,115,000
Outstanding, beginning of period, weighted average grant price	$ 56.14	$ 54.16	$ 45.72
Granted, shares	9,000	13,000	244,000
Granted, weighted average grant price	$ 138.57	$ 101.81	$ 60.48
Vested, shares	(231,000)	(280,000)	(370,000)
Vested, weighted average grant price	$ 57.35	$ 51.62	$ 36.02
Canceled, shares	0	(8,000)	(61,000)
Canceled, weighted average grant price	$ 0.00	$ 56.50	$ 35.25
Outstanding, end of period, shares	431,000	653,000	928,000
Outstanding, end of period, weighted average grant price	$ 57.24	$ 56.14	$ 54.16
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning of period, shares	288,000	327,000	273,000
Outstanding, beginning of period, weighted average grant price	$ 74.73	$ 61.79	$ 54.86
Granted, shares	153,000	73,000	142,000
Granted, weighted average grant price	$ 136.54	$ 109.96	$ 71.33
Vested, shares	(104,000)	(88,000)	(52,000)
Vested, weighted average grant price	$ 70.23	$ 61.17	$ 56.59
Canceled, shares	(12,000)	(24,000)	(36,000)
Canceled, weighted average grant price	$ 112.53	$ 55.28	$ 54.47
Outstanding, end of period, shares	325,000	288,000	327,000
Outstanding, end of period, weighted average grant price	$ 104.01	$ 74.73	$ 61.79