Income Taxes (Details) - USD ($)	1 Months Ended			3 Months Ended		12 Months Ended
	Aug. 31, 2016	Jun. 30, 2016	Feb. 29, 2016	Mar. 31, 2017	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Examination [Line Items]
Number Of Years Of Tax Loss Carryback Period							2 years
Tax Adjustments, Settlements, and Unusual Provisions							$ 5,000,000	$ 17,000,000	$ 12,000,000	$ 15,000,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued				$ (4,300,000)		$ (3,400,000)	$ (100,000)
Interest Expense (Income) related to unrecognized tax benefits				(900,000)		(3,300,000)
Unrecognized Tax Benefits [Abstract]
Unrecognized tax benefit — Permanent tax positions				30,100,000		29,600,000
Unrecognized tax benefit — Temporary tax positions				105,300,000		104,100,000
Total unrecognized tax benefit				135,400,000		133,700,000
NOL and tax credit carryforwards				(45,600,000)		(43,800,000)
Upper bound of decrease in unrecognized tax benefit that is reasonably possible				60,000,000
Amounts accrued for penalties related to unrecognized tax benefits				0		$ 0
Internal Revenue Service (IRS)
Tax Audits [Abstract]
Year(s) under examination					2012 and 2013					2010 and 2011
Year of carryback claim under examination										2009
Potential Tax Adjustments				$ 14,000,000
Earliest year subject to examination				2009
Colorado
Tax Audits [Abstract]
Earliest year subject to examination				2009
Minnesota
Tax Audits [Abstract]
Year(s) under examination		2010 through 2014
Earliest year subject to examination				2009
Texas
Tax Audits [Abstract]
Year(s) under examination			2009 and 2010
Earliest year subject to examination				2009
Wisconsin
Tax Audits [Abstract]
Year(s) under examination	2012 and 2013
Earliest year subject to examination				2012