v3.19.1

Summary of business and significant accounting policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2019	Feb. 01, 2019	Jan. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity securities investment ownership percentage	4.00%
Marketable equity securities, at fair value	$ 77,356		$ 0
Equity method investment ownership percentage	22.00%
Equity method investments	$ 209		209
Cost method investment ownership percentage	1.00%
Non-marketable equity securities	$ 500		$ 500
Operating lease liabilities	40,029
Operating lease right of use asset	$ 37,367
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining operating lease terms	3 years
Lease renewal terms extension	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining operating lease terms	12 years
Lease renewal terms extension	10 years
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities		$ 40,600
Operating lease right of use asset		$ 38,000

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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