Acquisitions (Narrative) (Details) $ / shares in Units, CAD in Millions	3 Months Ended			6 Months Ended
	Oct. 31, 2016 USD ($) $ / shares shares	Oct. 31, 2016 CAD shares	Jan. 31, 2016 USD ($)	Jan. 31, 2017 USD ($)	Jan. 31, 2016 USD ($)	Oct. 17, 2016 USD ($)	Oct. 14, 2016 $ / shares	Jan. 19, 2016 USD ($)
Payments to Acquire Businesses, Net of Cash Acquired				$ 512,348,000	$ 20,245,000
Noncontrolling Interest, Increase from Business Combination				182,579,000
Goodwill Acquired During Period				956,086,000
Whistler Blackcomb [Member]
Business Acquisition, Date of Acquisition Agreement	Aug. 05, 2016	Aug. 05, 2016
Shares Purchased to Acquire Business | shares	38,500,000	38,500,000
Foreign Currency Exchange Rate, Translation							0.097294
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	3,746,000	3,746,000
Business Acquisition, Effective Date of Acquisition	Oct. 17, 2016	Oct. 17, 2016
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years	5 years
Noncontrolling Interest, Ownership Percentage by Parent	75.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	25.00%
Wilmot [Member]
Business Acquisition, Effective Date of Acquisition			Jan. 19, 2016
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			10 years
Business Combination, Consideration Transferred			$ 20,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment								$ 12,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill								400,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets								200,000
Goodwill Acquired During Period			$ 7,400,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable								$ 300,000
United States of America, Dollars | Whistler Blackcomb [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables						$ 37,567,000
Business Combination, Consideration Transferred	$ 1,087,203,000
Business Acquisition, Share Price | $ / shares	$ 13.31
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual				105,500,000
Business Combination, Consideration Transferred	$ 512,558,000
Business Combination, Consideration Transferred, Other	4,308,000
Total Estimated Purchase Consideration						1,274,090,000
Realized Investment Gains (Losses)	800,000
Goodwill, Purchase Accounting Adjustments				8,500,000
Payments to Acquire Businesses, Gross	509,200,000
Foreign Currency Transaction Gain (Loss), Realized	$ 3,400,000.0
Business Acquisition, Transaction Costs				3,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment						332,609,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill						152,035,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets						1,907,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets						144,922,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities						74,108,000
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned						574,645,000
Share Price | $ / shares							$ 153.41
Business Acquisition, Purchase Price Allocation, Real estate held for sale and investment						$ 8,216,000
Canada, Dollars | Whistler Blackcomb [Member]
Business Acquisition, Share Price | $ / shares	$ 17.50
Business Combination, Consideration Transferred | CAD		CAD 673.8
Noncontrolling Interests [Member]
Noncontrolling Interest, Increase from Business Combination	$ 182,579,000			182,579,000
Common Stock [Member] | Whistler Blackcomb [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	3,327,719	3,327,719
Exchangeable Shares [Member] | Whistler Blackcomb [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	418,095	418,095
Mountain [Member] | United States of America, Dollars | Whistler Blackcomb [Member]
Goodwill Acquired During Period				$ 956,086,000