Other Comprehensive Income (Loss) (Schedule of Items Reclassified out of AOCL) (Details) - USD ($) | 3 Months Ended | | |
Dec. 31, 2020 | Dec. 31, 2019 | Sep. 30, 2020 | Sep. 30, 2019 |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Amount reclassified | $ (71,600,000) | $ (42,600,000) | | |
Tax effect | 12,800,000 | 2,800,000 | | |
Net of tax | (58,800,000) | (39,800,000) | | |
Net activity | 36,900,000 | 21,200,000 | | |
Stockholders' Equity Attributable to Parent | 1,763,100,000 | | $ 1,726,100,000 | |
Available-for-sale Securities and Hedges [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | (3,400,000) | 900,000 | | |
Net of tax | (2,600,000) | 600,000 | | |
Prior to reclassification | (3,000,000) | (4,200,000) | | |
Other Comprehensive Income (Loss), before Tax | (6,400,000) | (3,300,000) | | |
Other Comprehensive Income (Loss), Tax | (1,500,000) | (700,000) | | |
Net activity | (4,900,000) | (2,600,000) | | |
Stockholders' Equity Attributable to Parent | (34,200,000) | 4,600,000 | (29,300,000) | $ 7,200,000 |
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | 0 | 0 | | |
Prior to reclassification | 41,300,000 | 23,100,000 | | |
Other Comprehensive Income (Loss), before Tax | 41,300,000 | 23,100,000 | | |
Other Comprehensive Income (Loss), Tax | 0 | 0 | | |
Net activity | 41,300,000 | 23,100,000 | | |
Stockholders' Equity Attributable to Parent | (69,400,000) | (122,300,000) | (110,700,000) | (145,400,000) |
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | 1,200,000 | 1,200,000 | | |
Tax effect | (200,000) | (300,000) | | |
Prior to reclassification | (500,000) | (200,000) | | |
Other Comprehensive Income (Loss), before Tax | 700,000 | 1,000,000 | | |
Other Comprehensive Income (Loss), Tax | (200,000) | (300,000) | | |
Net activity | 500,000 | 700,000 | | |
Stockholders' Equity Attributable to Parent | (39,700,000) | (43,600,000) | (40,200,000) | (44,300,000) |
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | 3,400,000 | (900,000) | | |
Accumulated Other Comprehensive Income (Loss) [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | (2,200,000) | 2,100,000 | | |
Prior to reclassification | 37,800,000 | 18,700,000 | | |
Other Comprehensive Income (Loss), before Tax | 35,600,000 | 20,800,000 | | |
Other Comprehensive Income (Loss), Tax | (1,300,000) | (400,000) | | |
Net activity | 36,900,000 | 21,200,000 | | |
Stockholders' Equity Attributable to Parent | (143,300,000) | (161,300,000) | (180,200,000) | (182,500,000) |
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Net of tax | 1,000,000 | 900,000 | | |
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Tax effect | 800,000 | (300,000) | | |
Foreign Exchange Forward [Member] | Available-for-sale Securities and Hedges [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Other Comprehensive Income (Loss), before Tax | (2,200,000) | (200,000) | | |
Net activity | (1,700,000) | (200,000) | | |
Stockholders' Equity Attributable to Parent | (2,000,000) | 0 | (300,000) | 200,000 |
Foreign Exchange Forward [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Other Comprehensive Income (Loss), Tax | 500,000 | 0 | | |
Interest Rate Swap [Member] | Available-for-sale Securities and Hedges [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Other Comprehensive Income (Loss), before Tax | 5,400,000 | 1,700,000 | | |
Net activity | 4,200,000 | 1,300,000 | | |
Stockholders' Equity Attributable to Parent | (31,500,000) | (3,900,000) | (35,700,000) | (5,200,000) |
Interest Rate Swap [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | 2,600,000 | (800,000) | | |
Tax effect | 600,000 | (200,000) | | |
Net of tax | 2,000,000 | (600,000) | | |
Prior to reclassification | 8,000,000 | 900,000 | | |
Other Comprehensive Income (Loss), Tax | (1,200,000) | (400,000) | | |
Foreign Exchange | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | 800,000 | (100,000) | | |
Tax effect | 200,000 | (100,000) | | |
Net of tax | 600,000 | 0 | | |
Prior to reclassification | (1,400,000) | (300,000) | | |
Currency Swap [Member] | Available-for-sale Securities and Hedges [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Stockholders' Equity Attributable to Parent | | | $ 6,700,000 | $ 12,200,000 |
Currency Swap [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | 0 | 0 | | |
Prior to reclassification | (9,600,000) | (4,800,000) | | |
Other Comprehensive Income (Loss), Tax | 2,200,000 | 1,100,000 | | |
Foreign Exchange Contract [Member] | Available-for-sale Securities and Hedges [Member] | | | | |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | | | | |
Other Comprehensive Income (Loss), before Tax | (9,600,000) | (4,800,000) | | |
Net activity | (7,400,000) | (3,700,000) | | |
Stockholders' Equity Attributable to Parent | $ (700,000) | $ 8,500,000 | | |