Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph g(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 14.F)
-URI http://asc.fasb.org/extlink&oid=6793087&loc=d3e301413-122809

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14
-Section F

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph 64
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Stock-Based Compensation Plans - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011 Year	Jun. 30, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock-based compensation cost recognized in income		$ 5,575,000	$ 5,166,000
Capitalized stock-based compensation cost		2,907,000	2,592,000
Incentive Compensation Plan 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of the options granted		$ 29.40
Expected annual dividends per share		4.00%
Expected volatility		35.00%
Risk-free interest rate		3.00%
Expected life in years		7
Maximum \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock fair values at the grant date		$ 147.75
Minimum \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock fair values at the grant date		$ 48.60
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested shares granted under restricted stock awards, outstanding	421,737	421,737
Restricted stock vesting during period		305,396
Grant date fair value of shares vested		34,882,000	9,467,000
Employee stock-based compensation cost recognized in income	187,000	187,000
Unrecognized compensation cost for unvested stock	8,948,000	8,948,000
Unrecognized compensation cost, expected weighted average Remaining Contractual period		2.76
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost for unvested stock	3,152,000	3,152,000
Unrecognized compensation cost, expected weighted average Remaining Contractual period		2.28
Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock-based compensation cost recognized in income		742,000	853,000
Capitalized stock-based compensation cost		416,000	466,000
Shares issued under performance plan (in shares)	397,370
Shares issued under performance plan	$ 51,153,000