Stock-Based Compensation Plans - Activity for the ELTI Plan, 2013 New Company LTIP, 2007 Incentive Plan and awards made outside of the stock-based compensation plans (Details) - Restricted stock - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ELTI Plan, the 2013 New Company LTIP, the 2007 Incentive Plan and awards made outside of stock-based compensation plans
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares outstanding, beginning of period (in shares)	341,000	673,000	379,000
Shares, granted (in shares)	217,000	26,000	611,000
Shares, vested (in shares)	(235,000)	(346,000)	(316,000)
Shares cancelled/forfeited (in shares)	(9,000)	(12,000)	(1,000)
Shares outstanding, end of period (in shares)	314,000	341,000	673,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares outstanding, weighted average grant date fair value, beginning of period (in dollars per share)	$ 55.77	$ 53.64	$ 42.97
Shares, weighted average grant date fair value, vested (in dollars per share)	58.91	53.70	53.90
Shares, weighted average grant date fair value, granted (in dollars per share)	108.73	88.58	60.21
Shares, weighted average grant date fair value, cancelled/forfeited (in dollars per share)	93.04	60.41	38.75
Shares outstanding, weighted average grant date fair value, end of period (in dollars per share)	$ 87.31	$ 55.77	$ 53.64
Market Condition & Performance-Based Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares outstanding, beginning of period (in shares)		324,000
Shares outstanding, end of period (in shares)			324,000
Market Condition & Performance-Based Awards | ELTI Plan, the 2013 New Company LTIP, the 2007 Incentive Plan and awards made outside of stock-based compensation plans
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares outstanding, beginning of period (in shares)	85,000	324,000	60,000
Shares, granted (in shares)	27,000	0	324,000
Shares, vested (in shares)	(85,000)	(239,000)	(60,000)
Shares cancelled/forfeited (in shares)	0	0	0
Shares outstanding, end of period (in shares)	27,000	85,000	324,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares outstanding, weighted average grant date fair value, beginning of period (in dollars per share)	$ 54.32	$ 53.71	$ 45.90
Shares, weighted average grant date fair value, vested (in dollars per share)	48.31	53.49	45.90
Shares, weighted average grant date fair value, granted (in dollars per share)	154.90	0.00	53.71
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)	$ 154.90	$ 54.32	$ 53.71
Service Period Awards | ELTI Plan, the 2013 New Company LTIP, the 2007 Incentive Plan and awards made outside of stock-based compensation plans
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares outstanding, beginning of period (in shares)	256,000	349,000	319,000
Shares, granted (in shares)	190,000	26,000	287,000
Shares, vested (in shares)	(150,000)	(107,000)	(256,000)
Shares cancelled/forfeited (in shares)	(9,000)	(12,000)	(1,000)
Shares outstanding, end of period (in shares)	287,000	256,000	349,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares outstanding, weighted average grant date fair value, beginning of period (in dollars per share)	$ 56.24	$ 53.58	$ 42.42
Shares, weighted average grant date fair value, vested (in dollars per share)	64.87	54.15	59.54
Shares, weighted average grant date fair value, granted (in dollars per share)	102.09	88.58	67.55
Shares, weighted average grant date fair value, cancelled/forfeited (in dollars per share)	93.04	60.41	38.75
Shares outstanding, weighted average grant date fair value, end of period (in dollars per share)	$ 80.90	$ 56.24	$ 53.58