Shareholder Report, Holdings (Details)	Mar. 31, 2025
C000004623 [Member] | Canadian Natural Resources Ltd [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.90%	[1]
C000004623 [Member] | Freeport McMoRan Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[1]
C000004623 [Member] | International Paper Co [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[1]
C000004623 [Member] | Diamondback Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[1]
C000004623 [Member] | Permian Resources Corp [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[1]
C000004623 [Member] | Phillips 66 [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[1]
C000004623 [Member] | BP PLC ADR [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.40%	[1]
C000004623 [Member] | Suncor Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%	[1]
C000004623 [Member] | Crescent Energy Co Cl A [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%	[1]
C000004623 [Member] | Anglo American PLC [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%	[1]
C000004623 [Member] | Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	48.60%
C000004623 [Member] | Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000004623 [Member] | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000004623 [Member] | Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	44.00%
C000004623 [Member] | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000004623 [Member] | Net Other Assets and Liabilities [Member]
Holdings [Line Items]
Percent of Net Asset Value	(1.10%)
C000004625 [Member] | Canadian Natural Resources Ltd [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.90%	[2]
C000004625 [Member] | Freeport McMoRan Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[2]
C000004625 [Member] | International Paper Co [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[2]
C000004625 [Member] | Diamondback Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[2]
C000004625 [Member] | Permian Resources Corp [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[2]
C000004625 [Member] | Phillips 66 [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[2]
C000004625 [Member] | BP PLC ADR [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.40%	[2]
C000004625 [Member] | Suncor Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%	[2]
C000004625 [Member] | Crescent Energy Co Cl A [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%	[2]
C000004625 [Member] | Anglo American PLC [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%	[2]
C000004625 [Member] | Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	48.60%
C000004625 [Member] | Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000004625 [Member] | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000004625 [Member] | Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	44.00%
C000004625 [Member] | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000004625 [Member] | Net Other Assets and Liabilities [Member]
Holdings [Line Items]
Percent of Net Asset Value	(1.10%)
C000004626 [Member] | Canadian Natural Resources Ltd [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.90%	[3]
C000004626 [Member] | Freeport McMoRan Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[3]
C000004626 [Member] | International Paper Co [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[3]
C000004626 [Member] | Diamondback Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[3]
C000004626 [Member] | Permian Resources Corp [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[3]
C000004626 [Member] | Phillips 66 [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[3]
C000004626 [Member] | BP PLC ADR [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.40%	[3]
C000004626 [Member] | Suncor Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%	[3]
C000004626 [Member] | Crescent Energy Co Cl A [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%	[3]
C000004626 [Member] | Anglo American PLC [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%	[3]
C000004626 [Member] | Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	48.60%
C000004626 [Member] | Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000004626 [Member] | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000004626 [Member] | Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	44.00%
C000004626 [Member] | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000004626 [Member] | Net Other Assets and Liabilities [Member]
Holdings [Line Items]
Percent of Net Asset Value	(1.10%)
C000162241 [Member] | Canadian Natural Resources Ltd [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.90%	[4]
C000162241 [Member] | Freeport McMoRan Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[4]
C000162241 [Member] | International Paper Co [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.80%	[4]
C000162241 [Member] | Diamondback Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[4]
C000162241 [Member] | Permian Resources Corp [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[4]
C000162241 [Member] | Phillips 66 [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.70%	[4]
C000162241 [Member] | BP PLC ADR [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.40%	[4]
C000162241 [Member] | Suncor Energy Inc [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.10%	[4]
C000162241 [Member] | Crescent Energy Co Cl A [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.00%	[4]
C000162241 [Member] | Anglo American PLC [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.80%	[4]
C000162241 [Member] | Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	48.60%
C000162241 [Member] | Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000162241 [Member] | Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000162241 [Member] | Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	44.00%
C000162241 [Member] | Investment Companies [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000162241 [Member] | Net Other Assets and Liabilities [Member]
Holdings [Line Items]
Percent of Net Asset Value	(1.10%)

[1] Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.

[2] Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.

[3] Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.

[4] Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.