Fair Value Measurements - Changes in Level 3 Fair Value Measurements (Details) - Recurring Fair Value Measurements - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015 |
Available-for-sale | Fixed maturities | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | $ 392.7 | $ 396.5 | $ 378.8 | $ 412.2 |
Total realized/unrealized gains (losses) included in net income, assets | (0.2) | (0.2) | (0.4) | (0.2) |
Total realized/unrealized gains (losses) included in other comprehensive income, assets | (0.8) | (5.4) | (1.7) | (1) |
Net purchases, sales, issuances and settlements, assets | 19.5 | 9.4 | 38.5 | 31.9 |
Transfers into Level 3, assets | 15.7 | 6.7 | 15.7 | 26.2 |
Transfers out of Level 3, assets | (32.6) | (29.7) | (36.6) | (91.8) |
Ending balance, assets | 394.3 | 377.3 | 394.3 | 377.3 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | (0.2) | (0.2) | (0.4) | (0.3) |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | 24.2 | 20.1 | 64.8 | 59.2 |
Sales, assets | | (2.1) | (9.3) | (5.7) |
Settlements, assets | (4.7) | (8.6) | (17) | (21.6) |
Net purchases, sales, issuances and settlements, assets | 19.5 | 9.4 | 38.5 | 31.9 |
Available-for-sale | Non-U.S. governments | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 97.8 | 40.6 | 79.1 | 38.7 |
Total realized/unrealized gains (losses) included in net income, assets | | (0.1) | (0.1) | (0.1) |
Total realized/unrealized gains (losses) included in other comprehensive income, assets | | (0.2) | 2.5 | 0.1 |
Net purchases, sales, issuances and settlements, assets | 2.3 | 5.3 | 18.6 | 6.9 |
Transfers out of Level 3, assets | (32.6) | | (32.6) | |
Ending balance, assets | 67.5 | 45.6 | 67.5 | 45.6 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | | (0.1) | (0.1) | (0.1) |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | 2.6 | 5.6 | 19.3 | 7.5 |
Settlements, assets | (0.3) | (0.3) | (0.7) | (0.6) |
Net purchases, sales, issuances and settlements, assets | 2.3 | 5.3 | 18.6 | 6.9 |
Available-for-sale | Corporate debt securities | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 222.7 | 237 | 223.9 | 245.6 |
Total realized/unrealized gains (losses) included in net income, assets | (0.2) | | (0.3) | (0.1) |
Total realized/unrealized gains (losses) included in other comprehensive income, assets | (1.1) | (4.6) | (3.7) | (0.9) |
Net purchases, sales, issuances and settlements, assets | 4.6 | 7.7 | 7.8 | 23.7 |
Transfers into Level 3, assets | 15.7 | 6.7 | 15.7 | 26.2 |
Transfers out of Level 3, assets | | (19.8) | (1.7) | (67.5) |
Ending balance, assets | 241.7 | 227 | 241.7 | 227 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | (0.2) | (0.1) | (0.3) | (0.2) |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | 7.9 | 14.5 | 31.8 | 41.6 |
Sales, assets | | (2.1) | (9.3) | (5.7) |
Settlements, assets | (3.3) | (4.7) | (14.7) | (12.2) |
Net purchases, sales, issuances and settlements, assets | 4.6 | 7.7 | 7.8 | 23.7 |
Available-for-sale | Commercial mortgage-backed securities | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 2.4 | | 4.8 | |
Net purchases, sales, issuances and settlements, assets | 13.1 | | 13 | |
Transfers out of Level 3, assets | | | (2.3) | |
Ending balance, assets | 15.5 | | 15.5 | |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | 13.7 | | 13.7 | |
Settlements, assets | (0.6) | | (0.7) | |
Net purchases, sales, issuances and settlements, assets | 13.1 | | 13 | |
Available-for-sale | Collateralized debt obligations | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 62.8 | 63.6 | 63.5 | 64.2 |
Total realized/unrealized gains (losses) included in net income, assets | | (0.1) | | |
Total realized/unrealized gains (losses) included in other comprehensive income, assets | 0.2 | | (0.5) | (0.1) |
Net purchases, sales, issuances and settlements, assets | (0.2) | (0.2) | (0.2) | (0.8) |
Ending balance, assets | 62.8 | 63.3 | 62.8 | 63.3 |
Gross purchases, sales, issuances and settlements | | | | |
Settlements, assets | (0.2) | (0.2) | (0.2) | (0.8) |
Net purchases, sales, issuances and settlements, assets | (0.2) | (0.2) | (0.2) | (0.8) |
Available-for-sale | Other debt obligations | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 7 | 55.3 | 7.5 | 63.7 |
Total realized/unrealized gains (losses) included in other comprehensive income, assets | 0.1 | (0.6) | | (0.1) |
Net purchases, sales, issuances and settlements, assets | (0.3) | (3.4) | (0.7) | 2.1 |
Transfers out of Level 3, assets | | (9.9) | | (24.3) |
Ending balance, assets | 6.8 | 41.4 | 6.8 | 41.4 |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | | | | 10.1 |
Settlements, assets | (0.3) | (3.4) | (0.7) | (8) |
Net purchases, sales, issuances and settlements, assets | (0.3) | (3.4) | (0.7) | 2.1 |
Available-for-sale | Equity securities | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 4.1 | 4.1 | 4.1 | 4.1 |
Total realized/unrealized gains (losses) included in net income, assets | (1.3) | | (1.3) | |
Total realized/unrealized gains (losses) included in other comprehensive income, assets | (0.1) | | (0.1) | |
Ending balance, assets | 2.7 | 4.1 | 2.7 | 4.1 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | (1.4) | | (1.4) | |
Trading | Fixed maturities | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 135.8 | 140.2 | 135.5 | 139.7 |
Total realized/unrealized gains (losses) included in net income, assets | | (0.5) | 0.3 | 0.2 |
Net purchases, sales, issuances and settlements, assets | (18) | 0.1 | (18) | (0.1) |
Ending balance, assets | 117.8 | 139.8 | 117.8 | 139.8 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | | (0.5) | 0.4 | 0.1 |
Gross purchases, sales, issuances and settlements | | | | |
Sales, assets | (18) | | (18) | (0.2) |
Settlements, assets | | 0.1 | | 0.1 |
Net purchases, sales, issuances and settlements, assets | (18) | 0.1 | (18) | (0.1) |
Derivative assets | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 59.1 | 60.2 | 47.2 | 53.7 |
Total realized/unrealized gains (losses) included in net income, assets | 1.7 | (15) | 13.2 | (11) |
Net purchases, sales, issuances and settlements, assets | 0.3 | (0.1) | 0.7 | 2.4 |
Ending balance, assets | 61.1 | 45.1 | 61.1 | 45.1 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | 2.4 | (15) | 14.4 | (10.8) |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | | | | 2.5 |
Sales, assets | 0.3 | (0.1) | 0.7 | (0.1) |
Net purchases, sales, issuances and settlements, assets | 0.3 | (0.1) | 0.7 | 2.4 |
Other investments | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 35.9 | 28.6 | 35.1 | 127.2 |
Total realized/unrealized gains (losses) included in net income, assets | 0.1 | 0.2 | 0.7 | 4 |
Net purchases, sales, issuances and settlements, assets | 0.1 | 0.9 | 0.3 | (66.5) |
Transfers out of Level 3, assets | | | | (35) |
Ending balance, assets | 36.1 | 29.7 | 36.1 | 29.7 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | 0.1 | 0.2 | 0.7 | 4 |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | 0.1 | 0.9 | 0.3 | 1.2 |
Sales, assets | | | | (67.7) |
Net purchases, sales, issuances and settlements, assets | 0.1 | 0.9 | 0.3 | (66.5) |
Separate account assets | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, assets | 7,094.5 | 6,030.6 | 7,013.9 | 5,891.4 |
Total realized/unrealized gains (losses) included in net income, assets | 140.2 | 239.2 | 293.1 | 454.9 |
Total realized/unrealized gains (losses) included in other comprehensive income, assets | | | (0.1) | |
Net purchases, sales, issuances and settlements, assets | 174.2 | 136.3 | 101.2 | 59.7 |
Transfers into Level 3, assets | 0.1 | | 0.9 | 0.1 |
Transfers out of Level 3, assets | (0.7) | (0.1) | (0.7) | (0.1) |
Ending balance, assets | 7,408.3 | 6,406 | 7,408.3 | 6,406 |
Changes in unrealized gains (losses) included in net income relating to positions still held, assets | 95.9 | 240.8 | 305.7 | 439.6 |
Gross purchases, sales, issuances and settlements | | | | |
Purchases, assets | 233.9 | 221.8 | 290.1 | 361 |
Sales, assets | (5.4) | 5.3 | (66.1) | (159.4) |
Issuances, assets | (47.2) | (96.5) | (140) | (145.8) |
Settlements, assets | (7.1) | 5.7 | 17.2 | 3.9 |
Net purchases, sales, issuances and settlements, assets | 174.2 | 136.3 | 101.2 | 59.7 |
Investment contracts | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, liabilities | (213) | (228.7) | (177.4) | (176.4) |
Total realized/unrealized gains (losses) included in net income, liabilities | (113) | 108.6 | (151.3) | 57.6 |
Net purchases, sales, issuances and settlements, liabilities | 1.7 | 3.1 | 4.4 | 1.8 |
Ending balance, liabilities | (324.3) | (117) | (324.3) | (117) |
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities | (114.3) | 107 | (153.4) | 54.9 |
Gross purchases, sales, issuances and settlements | | | | |
Issuances, liabilities | | 0.8 | 1.1 | (2.3) |
Settlements, liabilities | 1.7 | 2.3 | 3.3 | 4.1 |
Net purchases, sales, issuances and settlements, liabilities | 1.7 | 3.1 | 4.4 | 1.8 |
Derivative liabilities | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, liabilities | (36.1) | (50.8) | (50.5) | (35.5) |
Total realized/unrealized gains (losses) included in net income, liabilities | 6.9 | 12.9 | 20.5 | (2.9) |
Total realized/unrealized gains (losses) included in other comprehensive income, liabilities | | 0.9 | 0.5 | 1.2 |
Net purchases, sales, issuances and settlements, liabilities | 0.7 | | 1 | 0.2 |
Ending balance, liabilities | (28.5) | (37) | (28.5) | (37) |
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities | 5.1 | 12.8 | 17.3 | (3) |
Gross purchases, sales, issuances and settlements | | | | |
Sales, liabilities | 0.7 | | 1 | 0.2 |
Net purchases, sales, issuances and settlements, liabilities | 0.7 | | 1 | 0.2 |
Other liabilities | | | | |
Changes in Level 3 fair value measurements rollforward, assets and liabilities | | | | |
Beginning balance, liabilities | (73.1) | (65.3) | (68.1) | (66.3) |
Total realized/unrealized gains (losses) included in net income, liabilities | (2.9) | (2.2) | (7.9) | (1.2) |
Net purchases, sales, issuances and settlements, liabilities | 17.4 | | 17.4 | |
Ending balance, liabilities | (58.6) | (67.5) | (58.6) | (67.5) |
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities | (2.4) | $ (2.2) | (6.2) | $ (1.3) |
Gross purchases, sales, issuances and settlements | | | | |
Sales, liabilities | 17.4 | | 17.4 | |
Net purchases, sales, issuances and settlements, liabilities | $ 17.4 | | $ 17.4 | |