Fair Value Measurements - Major Terms of Interest Rate Swap Agreements (Details) - Designated as hedging instrument $ in Millions	Sep. 30, 2019 USD ($)
Derivative [Line Items]
Notional Amount (In millions)	$ 3,000
Interest rate swap at 2.274%
Derivative [Line Items]
Notional Amount (In millions)	$ 250
Fixed Rate Paid	2.274%
Variable Rate Received	2.112%
Interest rate swap at 2.828%
Derivative [Line Items]
Notional Amount (In millions)	$ 200
Fixed Rate Paid	2.828%
Variable Rate Received	2.112%
Interest rate swap at 2.739%
Derivative [Line Items]
Notional Amount (In millions)	$ 600
Fixed Rate Paid	2.739%
Variable Rate Received	2.112%
Interest rate swap at 2.153%
Derivative [Line Items]
Notional Amount (In millions)	$ 250
Fixed Rate Paid	2.153%
Variable Rate Received	2.112%
Interest rate swap at 2.196%
Derivative [Line Items]
Notional Amount (In millions)	$ 250
Fixed Rate Paid	2.196%
Variable Rate Received	2.112%
Interest rate swap at 2.788%
Derivative [Line Items]
Notional Amount (In millions)	$ 400
Fixed Rate Paid	2.788%
Variable Rate Received	2.112%
Interest rate swap at 2.828%
Derivative [Line Items]
Notional Amount (In millions)	$ 200
Fixed Rate Paid	2.828%
Variable Rate Received	2.112%
Interest rate swap at 2.172%
Derivative [Line Items]
Notional Amount (In millions)	$ 250
Fixed Rate Paid	2.172%
Variable Rate Received	2.112%
Interest rate swap at 2.731%
Derivative [Line Items]
Notional Amount (In millions)	$ 200
Fixed Rate Paid	2.731%
Variable Rate Received	2.112%
Interest rate swap at 2.707%
Derivative [Line Items]
Notional Amount (In millions)	$ 400
Fixed Rate Paid	2.707%
Variable Rate Received	2.112%