Shareholder Report, Holdings (Details)	Jun. 30, 2025
C000030208 \| Securities Lending Collateral
Holdings [Line Items]
Percent of Net Asset Value	0.50%
C000030208 \| Foreign Government/Agency
Holdings [Line Items]
Percent of Net Asset Value	2.10%
C000030208 \| Cash Equivalents
Holdings [Line Items]
Percent of Net Asset Value	3.20%
C000030208 \| Corporate Bonds
Holdings [Line Items]
Percent of Net Asset Value	93.50%
C000030209 \| Cash Equivalents
Holdings [Line Items]
Percent of Net Asset Value	4.00%
C000030209 \| Independent Energy
Holdings [Line Items]
Percent of Net Asset Value	3.70%
C000030209 \| Gaming
Holdings [Line Items]
Percent of Net Asset Value	4.00%
C000030209 \| Automotive
Holdings [Line Items]
Percent of Net Asset Value	4.20%
C000030209 \| Midstream
Holdings [Line Items]
Percent of Net Asset Value	4.20%
C000030209 \| Building Materials
Holdings [Line Items]
Percent of Net Asset Value	4.60%
C000030209 \| Health Care
Holdings [Line Items]
Percent of Net Asset Value	5.60%
C000030209 \| Cable Satellite
Holdings [Line Items]
Percent of Net Asset Value	5.80%
C000030209 \| Insurance - P&C
Holdings [Line Items]
Percent of Net Asset Value	9.40%
C000030209 \| Technology
Holdings [Line Items]
Percent of Net Asset Value	12.60%
C000030211 \| Cash Equivalents
Holdings [Line Items]
Percent of Net Asset Value	3.10%
C000030211 \| Agency Risk Transfer Securities
Holdings [Line Items]
Percent of Net Asset Value	0.30%
C000030211 \| Non-Agency Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	1.30%
C000030211 \| Asset-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	2.60%
C000030211 \| Collaterized Mortgage Obligations
Holdings [Line Items]
Percent of Net Asset Value	11.60%
C000030211 \| U.S. Government Agency Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	93.80%