Restructuring Charges - Summary of Amounts Incurred (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended	27 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Oct. 30, 2015	Jan. 27, 2017
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	$ 4,035	$ 26,659		$ 133,662
Pension Plan
Restructuring Cost and Reserve [Line Items]
Contractual termination benefits	0	9,600
Employee severance and termination costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	743	21,153		78,678
Asset impairment charges
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges				18,962
Accelerated depreciation
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	0	4,779		22,144
Other costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	3,292	727		13,878
Underground
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	3,766	25,700		105,278
Underground | Pension Plan
Restructuring Cost and Reserve [Line Items]
Contractual termination benefits		9,600	$ 2,600
Underground | Employee severance and termination costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	474	20,194		57,929
Underground | Asset impairment charges
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges				18,962
Underground | Accelerated depreciation
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges		4,779		15,404
Underground | Other costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	3,292	727		12,983
Surface
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	269	564		25,404
Surface | Employee severance and termination costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	269	564		17,769
Surface | Asset impairment charges
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges				0
Surface | Accelerated depreciation
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges		0		6,740
Surface | Other costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	0	0		895
Corporate
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	0	395		2,980
Corporate | Employee severance and termination costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	0	395		2,980
Corporate | Asset impairment charges
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges				0
Corporate | Accelerated depreciation
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges		0		0
Corporate | Other costs
Restructuring Cost and Reserve [Line Items]
Total restructuring and related charges	$ 0	$ 0		$ 0