Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2013

Schedule Of Risk Free Interest Rate

Assumptions	2013	2012	2011
Risk-free interest rate	1.5%	0.6%	0.9%
Expected dividend yield	–	–	–
Expected volatility	38.6%	58.2%	58.1%
Expected term	5 years	5 years	5 years

Summary of Stock Option Activity, Options Outstanding

	2013			2012			2011
			Weighted			Weighted			Weighted
			Average			Average			Average
	Number		Exercise	Number		Exercise	Number		Exercise
	of Shares		Price	of Shares		Price	of Shares		Price
Options outstanding at January 1	3,649,520	$	29.84	4,741,732	$	21.24	4,769,122	$	16.13
Granted	571,166		38.95	613,120		34.34	853,478		36.64
Exercised	(833,132)		12.12	(1,607,784)		5.71	(850,659)		7.54
Forfeited or expired	(74,861)		37.31	(97,548)		37.76	(30,209)		35.46
Options outstanding at December 31	3,312,693	$	35.70	3,649,520	$	29.84	4,741,732	$	21.24

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

	Options Outstanding						Options Exercisable
				Weighted						Weighted
				Average						Average
	Options	Weighted		Remaining	Aggregate		Options	Weighted		Remaining	Aggregate
	Outstanding at	Average		Contractual	Intrinsic		Exercisable at	Average		Contractual	Intrinsic
Range of	December 31,	Exercise		Life	Value		December 31,	Exercise		Life	Value
Exercise Prices	2013	Price		(Years)	(thousands)		2013	Price		(Years)	(thousands)
$20.34-$29.69	273,134		27.31	1.2			265,025		27.29	1.1
$30.23-$35.91	1,087,218		33.09	4.3			677,387		32.32	3.4
$36.22-$39.91	1,587,066		37.56	5.4			803,412		36.74	4.4
$40.15-$51.47	365,275		41.64	3.0			358,004		41.62	2.9
	3,312,693	$	35.70	4.4	$	12,882	2,103,828	$	34.96	2.9	$	10,022

Summary of Restricted Stock Activity and Unvested Shares

	2013			2012			2011
			Weighted			Weighted			Weighted
			Average			Average			Average
	Number		Grant Date	Number		Grant Date	Number		Grant Date
	of Shares		Fair Value	of Shares		Fair Value	of Shares		Fair Value
Unvested shares at January 1	1,117,515	$	35.64	1,019,737	$	36.71	834,058	$	36.24
Granted	1,108,852		38.92	537,244		34.39	532,754		36.41
Vested	(381,676)		36.29	(344,164)		36.50	(294,358)		34.90
Forfeited	(73,769)		35.81	(95,302)		36.97	(52,717)		36.45
Unvested shares at December 31	1,770,922	$	37.55	1,117,515	$	35.64	1,019,737	$	36.71

Stock Options [Member]

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Text Block]

	2013		2012		2011
		(in thousands)
Stock-based compensation cost related to stock options – general and administrative expense	$	5,494	$	5,427	$	4,959
Stock-based compensation cost related to stock options – capitalized	$	4,812	$	4,468	$	3,365

Restricted Stock [Member]

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Text Block]

		2013		2012		2011
		(in thousands)
Stock-based compensation cost related to restricted stock grants   – general and administrative expense	$	7,432	$	6,368	$	5,591
Stock-based compensation cost related to restricted stock grants   – capitalized	$	7,469	$	5,994	$	5,162