Stock-based Compensation (Out Performance Plans) (Details) - USD ($)		12 Months Ended
	Jan. 10, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award
Share Based Compensation Expense		$ 33,980,000	$ 39,846,000	$ 36,641,000
Full Value Awards
Share Based Compensation Arrangement By Share Based Payment Award
Share Based Compensation Shares Available For Grant (in Shares)		2,929,000
Full Value Awards | Maximum
Share Based Compensation Arrangement By Share Based Payment Award
Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized (in Shares)		6,000,000
Not Full Value Awards | Maximum
Share Based Compensation Arrangement By Share Based Payment Award
Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized (in Shares)		12,000,000
Out Performance Plan
Share Based Compensation Arrangement By Share Based Payment Award
Share Based Compensation Expense		$ 11,055,000	15,531,000	$ 6,185,000
Out Performance Plan
Compensation Cost Not Yet Recognized		$ 5,752,000
Award vesting in three years		33.00%
Award versting in four years		33.00%
Award vesting in five years		34.00%
Compensation Cost Recognition Period		1 year 8 months
Out Performance Plan 2016
Out Performance Plan
Percentage of Notional Amount Granted		86.70%
Out of performance plan notional amount		$ 40,000,000
Grant-Date Fair Value		$ 11,800,000
OPP Units Earned, String		To be determined in 2019
Award Amortization Period		5 years
Required award holding period after vesting		1 year
Out Performance Plan 2016 | Absolute Component
Out Performance Plan
Required Shareholder Return Per Year		7.00%
Required Shareholder Return Three Year		21.00%
Duration Of Performance Measurement Period		3 years
Out Performance Plan 2016 | Relative Component
Out Performance Plan
Required Shareholder Return Under Relative Component		6.00%
Percentage Of Shareholder Return Under Which No Awards Will Be Earned		0.00%
Duration Of Performance Measurement Period		3 years
Out Performance Plan 2015
Out Performance Plan
Percentage of Notional Amount Granted		84.50%
Out of performance plan notional amount		$ 40,000,000
Grant-Date Fair Value		$ 9,120,000
OPP Units Earned, String		To be determined in 2018
Award Amortization Period		5 years
Required award holding period after vesting		1 year
Out Performance Plan 2015 | Absolute Component
Out Performance Plan
Required Shareholder Return Per Year		7.00%
Required Shareholder Return Three Year		21.00%
Duration Of Performance Measurement Period		3 years
Out Performance Plan 2015 | Relative Component
Out Performance Plan
Required Shareholder Return Under Relative Component		6.00%
Percentage Of Shareholder Return Under Which No Awards Will Be Earned		0.00%
Duration Of Performance Measurement Period		3 years
Out Performance Plan 2014
Out Performance Plan
Percentage of Notional Amount Granted		58.90%
Out of performance plan notional amount		$ 50,000,000
Grant-Date Fair Value		$ 8,202,000
OPP Units Earned		297,495
Award Amortization Period		5 years
Required award holding period after vesting		1 year
Out Performance Plan 2014 | Subsequent Event
Out Performance Plan
Awards earned (in percentage)	99.50%
Out Performance Plan 2013 to 2015
Out Performance Plan
Additional Expense From Acceleration Of Vesting			$ 7,834,000
Revised Age Limit For Awards Vesting Criteria			65 years