Share-Based Compensation (Details) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) Rate $ / shares shares	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Rate $ / shares shares	Jun. 30, 2016 USD ($)
Share-based compensation, allocation and classification in financial statements [Abstract]
Compensation cost charged to income for the Company's share-based compensation plans | $	$ 2.4	$ 2.6	$ 5.5	$ 6.0
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount | $		$ 0.5	$ 0.3	1.3
Restricted Stock Units (RSUs) [Member]
Summary of non-option activity, additional disclosures [Abstract]
Awards under the 2008 Omnibus Plan			represents the right to receive upon vesting one share of common stock, as well as a cash payment upon vesting equal to the aggregate cash dividends that would have been paid on such shares of common stock during the vesting period
Weighted average grant-date fair value | $ / shares			$ 67.43
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $	$ 6.5		$ 6.5
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			1 year 12 months
Summary of non-option activity [Roll Forward]
Outstanding at January 1, 2017			231,903
Vested			(111,617)
Granted			69,775
Forfeited			(6,922)
Outstanding at June 30, 2017	183,139		183,139
Outstanding at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares			$ 70.40
Vested, weighted average grant date fair value (in dollars per share) | $ / shares			66.33
Granted, weighted average grant date fair value (in dollars per share) | $ / shares			67.43
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares			71.42
Outstanding at end of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 71.71		$ 71.71
2008 Omnibus Plan [Member]
Deferred compensation arrangements [Abstract]
Aggregate number of Company common shares or Operating Partnership units approved for awards under the 2008 Omnibus Plan, amended (in shares)	8,500,000		8,500,000
The ratio at which non-option awards granted after the 2010 amendment are deducted from the shares available for grant | Rate	1.85		1.85
The ratio at which non-option awards granted prior to the 2010 amendment are deducted from the shares available for grant | Rate	2.85		2.85
The ratio at which options awards granted are deducted from the shares available for grant			one-for-one
Profits Units [Member]
Summary of non-option activity, additional disclosures [Abstract]
Awards under the 2008 Omnibus Plan			represents a contingent right to receive a TRG Unit upon vesting and the satisfaction of certain tax-driven requirements and, as to the TSR and NOI Performance-based TRG Profits Units the satisfaction of certain performance-based requirements. Until vested, a TRG Profits Unit entitles the holder to only one-tenth of the distributions otherwise payable by TRG on a TRG Unit. Therefore, the Company accounts for these TRG Profits Units as participating securities in the Operating Partnership. A portion of the TRG Profits Units award represents estimated cash distributions that otherwise would have been payable during the vesting period and, upon vesting, there will be an adjustment in actual number of TRG Profits Units realized under each award to reflect the Operating Partnership's actual cash distributions during the vesting period
Restricted TRG Profits Units [Member]
Summary of non-option activity, additional disclosures [Abstract]
Weighted average grant-date fair value | $ / shares			$ 57.84
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $	$ 4.0		$ 4.0
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			2 years 3 months 18 days
Summary of non-option activity [Roll Forward]
Outstanding at January 1, 2017			45,940
Granted			46,076
Outstanding at June 30, 2017	92,016		92,016
Outstanding at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares			$ 59.49
Granted, weighted average grant date fair value (in dollars per share) | $ / shares			57.84
Outstanding at end of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 58.66		58.66
TSR Performance-based TRG Profits Units [Member]
Summary of non-option activity, additional disclosures [Abstract]
Weighted average grant-date fair value | $ / shares			$ 23.14
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $	$ 3.8		$ 3.8
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			2 years 3 months 18 days
Summary of non-option activity [Roll Forward]
Outstanding at January 1, 2017			103,369
Granted			103,666
Outstanding at June 30, 2017	207,035		207,035
Outstanding at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares			$ 26.42
Granted, weighted average grant date fair value (in dollars per share) | $ / shares			23.14
Outstanding at end of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 24.78		24.78
NOI Performance-based TRG Profits Units [Member]
Summary of non-option activity, additional disclosures [Abstract]
Weighted average grant-date fair value | $ / shares			$ 19.35
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $	$ 3.0		$ 3.0
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			2 years 3 months 18 days
Summary of non-option activity [Roll Forward]
Outstanding at January 1, 2017			103,369
Granted			103,666
Outstanding at June 30, 2017	207,035		207,035
Outstanding at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares			$ 19.41
Granted, weighted average grant date fair value (in dollars per share) | $ / shares			19.35
Outstanding at end of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 19.38		$ 19.38
Performance Shares [Member]
Summary of non-option activity, additional disclosures [Abstract]
Awards under the 2008 Omnibus Plan			represents the right to receive upon vesting one share of the Company's common stock, as well as a cash payment upon vesting equal to the aggregate cash dividends that would have been paid on such shares of common stock from the award's grant date to the vesting date
Weighted average grant-date fair value | $ / shares			$ 80.16
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $	$ 1.2		$ 1.2
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			10 months 20 days
Summary of non-option activity [Roll Forward]
Outstanding at January 1, 2017			166,027
Granted			5,046
Outstanding at June 30, 2017	44,621		44,621
Outstanding at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares			$ 138.93
Granted, weighted average grant date fair value (in dollars per share) | $ / shares			80.16
Outstanding at end of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 106.91		$ 106.91
NOI Performance Shares [Member]
Summary of non-option activity, additional disclosures [Abstract]
Awards under the 2008 Omnibus Plan			represents the right to receive upon vesting one share of the Company's common stock, as well as a cash payment upon vesting equal to the aggregate cash dividends that would have been paid on such shares of common stock from the award's grant date to the vesting date
Weighted average grant-date fair value | $ / shares			$ 67.04
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $	$ 0.3		$ 0.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			2 years 8 months 12 days
Summary of non-option activity [Roll Forward]
Granted			5,046
Outstanding at June 30, 2017	5,046		5,046
Granted, weighted average grant date fair value (in dollars per share) | $ / shares			$ 67.04
Outstanding at end of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 67.04		$ 67.04
Employee Stock Option [Member]
Summary of option activity [Roll Forward]
Outstanding at June 30, 2017	107,997		107,997
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 45.90		$ 45.90
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term			8 months
Summary of option activity, additional disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			0
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options | $			$ 4.8	$ 3.8
Unissued Partnership Units Under Unit Option Deferral Election Member
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Options exercised under unit option deferral election plan (in shares)			3,000,000
The number of mature units tendered for the exercise of previously issued stock options under the unit option deferral election plan (in shares)			2,100,000
The number of units deferred under the unit option deferral election upon the exercise of previously issued stock options (in shares)			900,000
Date at which deferred partnership units begin to be issued			December 2022
Number of Annual Installments during which Deferred Partnership Units will be issued			five
2015 Grant [Member] | Performance Shares [Member]
Summary of non-option activity, additional disclosures [Abstract]
Actual Shares Issued Upon Vesting During Period			2,193.00
Summary of non-option activity [Roll Forward]
Vested			(2,885)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares			$ 112.30
2014 Grant [Member] | Performance Shares [Member]
Summary of non-option activity, additional disclosures [Abstract]
Actual Shares Issued Upon Vesting During Period			27,166.00
Summary of non-option activity [Roll Forward]
Vested			(43,803)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares			$ 88.10
2012 and 2013 Special Grants [Member] | Performance Shares [Member]
Summary of non-option activity, additional disclosures [Abstract]
Actual Shares Issued Upon Vesting During Period			0.00
Summary of non-option activity [Roll Forward]
Vested			(79,764)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares			$ 181.99