Stock-Based Compensation Plans - Activity for Awards Made Outside of Share-Based Compensation Plans (Details) - ELTI Plan, the 2013 New Company LTIP, the 2007 Incentive Plan and awards made outside of stock-based compensation plans - Restricted stock - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Shares
Shares outstanding, beginning of period (in shares)	314	341	673
Shares, granted (in shares)	127	217	26
Shares, vested (in shares)	(186)	(235)	(346)
Shares cancelled/forfeited (in shares)	(6)	(9)	(12)
Shares outstanding, end of period (in shares)	249	314	341
Weighted Average Grant Date Fair Value
Shares outstanding, weighted average grant date fair value, beginning of period (in dollars per share)	$ 87.31	$ 55.77	$ 53.64
Shares, weighted average grant date fair value, granted (in dollars per share)	134.60	108.73	88.58
Shares, weighted average grant date fair value, vested (in dollars per share)	70.81	58.91	53.70
Shares, weighted average grant date fair value, cancelled/forfeited (in dollars per share)	100.31	93.04	60.41
Shares outstanding, weighted average grant date fair value, end of period (in dollars per share)	$ 121.95	$ 87.31	$ 55.77
Market Condition & Performance-Based Awards
Number of Shares
Shares outstanding, beginning of period (in shares)	27	85	324
Shares, granted (in shares)	30	27	0
Shares, vested (in shares)	0	(85)	(239)
Shares cancelled/forfeited (in shares)	0	0	0
Shares outstanding, end of period (in shares)	57	27	85
Weighted Average Grant Date Fair Value
Shares outstanding, weighted average grant date fair value, beginning of period (in dollars per share)	$ 154.90	$ 54.32	$ 53.71
Shares, weighted average grant date fair value, granted (in dollars per share)	141.02	154.90	0.00
Shares, weighted average grant date fair value, vested (in dollars per share)	0.00	48.31	53.49
Shares, weighted average grant date fair value, cancelled/forfeited (in dollars per share)	0.00	0.00	0.00
Shares outstanding, weighted average grant date fair value, end of period (in dollars per share)	$ 147.67	$ 154.90	$ 54.32
Service Period Awards
Number of Shares
Shares outstanding, beginning of period (in shares)	287	256	349
Shares, granted (in shares)	97	190	26
Shares, vested (in shares)	(186)	(150)	(107)
Shares cancelled/forfeited (in shares)	(6)	(9)	(12)
Shares outstanding, end of period (in shares)	192	287	256
Weighted Average Grant Date Fair Value
Shares outstanding, weighted average grant date fair value, beginning of period (in dollars per share)	$ 80.90	$ 56.24	$ 53.58
Shares, weighted average grant date fair value, granted (in dollars per share)	132.64	102.09	88.58
Shares, weighted average grant date fair value, vested (in dollars per share)	70.81	64.87	54.15
Shares, weighted average grant date fair value, cancelled/forfeited (in dollars per share)	100.31	93.04	60.41
Shares outstanding, weighted average grant date fair value, end of period (in dollars per share)	$ 114.33	$ 80.90	$ 56.24