Compensation Plans Restricted Stock Units Under the Equity Incentive Compensation Plan (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Compensation plans
Stock-based compensation expense	$ 32,347,000	$ 30,185,000	$ 26,824,000
Restricted Stock Units (RSUs) [Member]
Compensation plans
Stock-based compensation expense	13,100,000	9,800,000	5,300,000
Unrecognized stock based compensation expense	19,300,000
Fair value of PSUs/RSUs Granted in Period	19,800,000	18,800,000	7,200,000
RSUs
Non-vested at the beginning of the period (in shares)	496,244	308,877	333,359
Granted (in shares)	329,939	379,332	98,952
Vested (in shares)	(207,376)	(166,672)	(105,820)
Forfeited (in shares)	(38,376)	(25,293)	(17,614)
Non-vested at the end of the period (in shares)	580,431	496,244	308,877
Weighted- Average Grant-Date Fair Value
Non-vested outstanding at the beginning of the period (in dollars per share)	$ 51.81	$ 44.33	$ 31.16
Granted (in dollars per share)	$ 60.01	$ 49.47	$ 72.69
Vested (in dollars per share)	$ 49.73	$ 32.72	$ 30.61
Forfeited (in dollars per share)	$ 54.37	$ 51.06	$ 36.80
Non-vested outstanding at the end of the period (in dollars per share)	$ 57.05	$ 51.81	$ 44.33
RSU Vesting Increment	0.33
Fair value of PSUs/RSUs Vested in Period	$ 10,300,000	$ 5,400,000	$ 3,200,000
Shares issued in period	207,378	166,670	105,820
Stock issued for settlement, PSU, net of tax (in shares)	139,391	116,813	72,305
Shares held for settlement of income and payroll tax obligations (in shares)	67,987	49,857	33,515
First Anniversary [Member] | Restricted Stock Units (RSUs) [Member]
Weighted- Average Grant-Date Fair Value
RSU Vesting Increment		0.14
Second Anniversary [Member] | Restricted Stock Units (RSUs) [Member]
Weighted- Average Grant-Date Fair Value
RSU Vesting Increment		0.29
Third Anniversary [Member] | Restricted Stock Units (RSUs) [Member]
Weighted- Average Grant-Date Fair Value
RSU Vesting Increment		0.57