Stock Incentive Compensation and Employee Benefit Plans (Equity Compensation Other than Options) (Details) - $ / shares	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Settled Restricted Stock Unit (CSRSUs)
Number of shares
Nonvested, beginning balance (in shares)	262,330	308,344	326,078
Awards granted (in shares)	0	98,067	135,119
Awards vested (in shares)	(108,344)	(122,088)	(133,278)
Awards forfeited (in shares)	(7,069)	(21,993)	(19,575)
Nonvested, Ending balance (in shares)	146,917	262,330	308,344
Performance Shares
Number of shares
Nonvested, beginning balance (in shares)	167,673	211,381	230,271
Awards granted (in shares)	83,475	64,947	77,045
Awards vested (in shares)	(16,456)	(62,499)	(58,032)
Awards forfeited (in shares)	(82,241)	(46,156)	(37,903)
Nonvested, Ending balance (in shares)	152,451	167,673	211,381
Weighted average grant-date fair value
Nonvested, beginning balance (in usd per share)	$ 53.11	$ 44.63	$ 41.40
Awards granted (in usd per share)	60.69	65.27	48.31
Awards vested (in usd per share)	53.79	43.51	38.30
Nonvested, ending balance (in usd per share)	$ 57.21	$ 53.11	$ 44.63
Employee restricted stock awards
Number of shares
Nonvested, beginning balance (in shares)	333,037	402,170	479,040
Awards granted (in shares)	255,799	116,345	179,003
Awards vested (in shares)	(139,454)	(185,478)	(255,873)
Awards forfeited (in shares)	(1,642)	0	0
Nonvested, Ending balance (in shares)	447,740	333,037	402,170
Weighted average grant-date fair value
Nonvested, beginning balance (in usd per share)	$ 120.93	$ 103.34	$ 94.95
Awards granted (in usd per share)	132.70	148.66	112.41
Awards vested (in usd per share)	112.70	100.17	93.98
Awards forfeited (in usd per share)	134.38	0.00	0.00
Nonvested, ending balance (in usd per share)	$ 130.37	$ 120.93	$ 103.34
Non-employee director restricted stock awards
Number of shares
Nonvested, beginning balance (in shares)	20,126	25,545	26,886
Awards granted (in shares)	12,169	12,193	14,727
Awards vested (in shares)	(9,761)	(17,612)	(16,068)
Awards forfeited (in shares)	0	0	0
Nonvested, Ending balance (in shares)	22,534	20,126	25,545
Weighted average grant-date fair value
Nonvested, beginning balance (in usd per share)	$ 131.09	$ 107.95	$ 97.61
Awards granted (in usd per share)	127.29	150.05	114.71
Awards vested (in usd per share)	123.59	110.66	96.83
Awards forfeited (in usd per share)	0.00	0.00	0.00
Nonvested, ending balance (in usd per share)	$ 132.29	$ 131.09	$ 107.95
Total restricted stock awards
Number of shares
Nonvested, beginning balance (in shares)	353,163	427,715	505,926
Awards granted (in shares)	267,968	128,538	193,730
Awards vested (in shares)	(149,215)	(203,090)	(271,941)
Awards forfeited (in shares)	(1,642)	0	0
Nonvested, Ending balance (in shares)	470,274	353,163	427,715
Weighted average grant-date fair value
Nonvested, beginning balance (in usd per share)	$ 121.51	$ 103.61	$ 95.09
Awards granted (in usd per share)	132.79	148.79	112.59
Awards vested (in usd per share)	113.41	101.08	94.15
Awards forfeited (in usd per share)	134.38	0.00	0.00
Nonvested, ending balance (in usd per share)	$ 130.46	$ 121.51	$ 103.61

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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