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Stockholders' Equity (Details) $ / shares in Millions, $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2017 $ / shares shares | Dec. 31, 2017 USD ($) $ / shares shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Dec. 31, 2014 USD ($) $ / shares shares
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Preferred stock, issued |  |  | 0 | 0 |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Granted (shares) |  |  | 682,000 | 669,000 | 675,000
Common stock shares available for future awards |  |  | 1,400,000 |  |
Shares vested |  |  | 154,000 | 23,000 | 18,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Nonvested beginning of the year (shares) | 1,852,000 | 1,852,000 | 1,652,000 | 1,376,000 | 927,000
Granted (shares) |  |  | 682,000 | 669,000 | 675,000
Vested (shares) |  |  | (154,000) | (23,000) | (18,000)
Forfeited (shares) |  |  | (328,000) | (370,000) | (208,000)
Nonvested end of the year (shares) |  |  | 1,852,000 | 1,652,000 | 1,376,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward] |  |  |  |  |
Beginning balance (in dollars per share) | $ / shares | $ 51.5 | $ 51.5 | $ 57.0 | $ 47.8 | $ 36.9
Granted (in dollars per share) | $ / shares |  |  | 8.4 | 20.8 | 20.3
Vested (in dollars per share) | $ / shares |  |  | (4.3) | (0.8) | (1.0)
Forfeited (in dollars per share) | $ / shares |  |  | (9.6) | (10.8) | (8.4)
Ending balance (in dollars per share) | $ / shares |  |  | $ 51.5 | $ 57.0 | $ 47.8
Retained Earnings Note Disclosure [Abstract] |  |  |  |  |
Undistributed earnings of investees accounted for under equity method | $ |  |  | $ 9.0 |  |
Restricted Stock [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Income target attainment measurement period |  |  | 3 years |  |
Share based compensation expense | $ |  |  |  | $ 5.5 | $ 2.4
Restricted stock and RSUs [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Share based compensation expense | $ |  |  | $ 11.2 |  |
Unrecognized compensation expense | $ |  |  | 12.9 |  |
Performance Awards [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation expense | $ |  |  | $ 4.2 |  |
TSR/TSRP Minimum Shares |  |  | 0 |  |
TSR/TSRP Target Shares |  |  | 538,000 |  |
TSR/TSRP Maximum Shares |  |  | 1,076,000 |  |
2016 LTIP [Member] | Restricted Share Units [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Granted (shares) |  |  | 587,661 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Granted (shares) |  |  | 587,661 |  |
Long-Term Shareholder Value (LTSV) 2015 [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance Metric, Percent Expected to be Attained |  |  | 85.00% |  |
Long-Term Shareholder Value (LTSV) 2015 [Member] | Restricted Stock [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Award vesting period |  |  | 3 years |  |
Long-Term Shareholder Value (LTSV) 2014 [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Shares vested |  |  | 116,989 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Vested (shares) |  |  | (116,989) |  |
PRSP 2012 [Member] | Restricted Stock [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Forfeited (shares) |  |  |  |  | (171,083)
PRSP 2013 [Member] | Restricted Stock [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Forfeited (shares) |  |  |  | (244,899) |
PRSP 2014 [Member] | Restricted Stock [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Forfeited (shares) |  |  | (214,571) |  |
TSR 2014-2016 [Member] | Performance Awards [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
TSR/TSRP Award Fair Value | $ |  |  | $ 12.5 |  |
Unrecognized compensation expense | $ |  |  | $ 4.2 |  |
TSR/TSRP Minimum Shares |  |  | 0 |  |
TSR/TSRP Target Shares |  |  | 276,000 |  |
TSR/TSRP Maximum Shares |  |  | 552,000 |  |
TSR and TSRP Awards [Member] | Performance Awards [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Performance measurement period |  |  | 3 years |  |
Share based compensation expense | $ |  |  | $ 6.6 | $ 10.6 | $ 9.8
Common stock shares available for future awards |  |  | 1,280,000 |  |
2016 PSU [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Income target attainment measurement period |  |  | 3 years |  |
Adjustment percentage |  |  | 20.00% |  |
Granted (shares) |  |  | 936,558 |  |
Grant date fair value | $ |  |  | $ 10.6 |  |
Performance measurement period |  |  | 3 years |  |
Share based compensation expense | $ |  |  | $ 1.9 |  |
Common stock shares available for future awards |  |  | 1,400,000 |  |
Unrecognized compensation expense | $ |  |  | $ 3.9 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Granted (shares) |  |  | 936,558 |  |
TSR 2014-2016 [Member] | Performance Awards [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
TSR/TSRP Award Fair Value | $ |  |  | $ 8.9 |  |
Unrecognized compensation expense | $ |  |  | $ 0.0 |  |
TSR/TSRP Minimum Shares |  |  | 0 |  |
TSR/TSRP Target Shares |  |  | 262,000 |  |
TSR/TSRP Maximum Shares |  |  | 524,000 |  |
Minimum [Member] | Restricted Stock [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Award vesting period |  |  | 3 years |  |
Minimum [Member] | TSR and TSRP Awards [Member] | Performance Awards [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Award multiplier |  |  | 0 |  |
Minimum [Member] | 2016 PSU [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Expected compensation cost | $ |  |  | $ 0.0 |  |
Attainment level range (percent) |  |  | 25.00% |  |
Maximum [Member] | Restricted Stock [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Award vesting period |  |  | 5 years |  |
Maximum [Member] | TSR and TSRP Awards [Member] | Performance Awards [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Award multiplier |  |  | 2 |  |
Maximum [Member] | 2016 PSU [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Expected compensation cost | $ |  |  | $ 15.9 |  |
Attainment level range (percent) |  |  | 150.00% |  |
Subsequent Event [Member] | TSR 2014-2016 [Member] | Performance Awards [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Shares vested | 164,988 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |  |  |  |  |
Vested (shares) | (164,988) |  |  |  |
Scenario, Forecast [Member] | Restricted stock and RSUs [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Share based compensation expense | $ |  | $ 9.5 |  |  |

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