Share-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended									0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Restricted Stock [Member]	Dec. 31, 2012 Restricted Stock [Member]	Dec. 31, 2011 Restricted Stock [Member]	Dec. 31, 2013 Stock Options [Member]	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2011 Stock Options [Member]	Jan. 02, 2014 Stock Award [Member]	Feb. 07, 2014 Stock Award [Member] Restricted Stock [Member]
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Share-based compensation incurred	$ 11,199	$ 10,371	$ 8,247	$ 10,907	$ 9,846	$ 7,308	$ 292	$ 525	$ 939
Capitalized share-based compensation	(1,024)	(908)	(663)
Share-based compensation expense	10,175	9,463	7,584
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at the beginning of year (in shares)	392,014
Outstanding at the beginning of year, Weighted-Average Exercise Price (in dollars per share)	$ 62.99
Granted (in shares)	0	0	0
Granted, Weighted-Average Exercise Price (in dollars per share)	$ 0.00
Exercised (in shares)	(16,554)
Exercised, Weighted-Average Exercise Price (in dollars per share)	$ 62.93
Forfeited or expired (in shares)	0
Forfeited or Expired, Weighted-Average Exercise Price (in dollars per share)	$ 0.00
Outstanding at the end of year (in shares)	375,460	392,014
Outstanding at the end of year, Weighted-Average Exercise Price (in dollars per share)	$ 63.00	$ 62.99
Outstanding at the end of year, Intrinsic Value	14,423
Exercisable at the end of year (in shares)	339,347
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 64.53
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	4 years 3 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 2 months
Exercisable, Aggregate Intrinsic Value	$ 12,514
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested at the beginning of year (in shares)	287,680
Unvested at the beginning of year, Weighted-Average Grant-Date Fair Value (in dollars per share)	$ 85.28
Granted (in shares)	109,033									5,914	110,353
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 106.70	$ 96.35	$ 81.94
Vested (in shares)	(98,280)
Vested, Weighted-Average Grant-Date Fair Value (in dollars per share)	$ 83.45
Forfeited (in shares)	(230)
Forfeited, Weighted-Average Grant-Date Fair Value (in dollars per share)	$ 86.86
Unvested at the end of year (in shares)	298,203	287,680
Unvested at the end of year, Weighted-Average Grant-Date Fair Value (in dollars per share)	$ 93.71	$ 85.28