The increase (decrease) during the reporting period in the aggregate amount of expenses incurred.

No definition available.

Name:	gdi_IncreaseDecreaseInLiabilities
Namespace Prefix:	gdi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Stock-Based Compensation Plans, Stock-Based Award Plan Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	May 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3.4
Accrued liabilities	305.4	$ 271.2
Unrecognized compensation expense	$ 28.1
Stock Options and Stock Appreciation Rights [Member]
Shares [Roll Forward]
Outstanding, beginning balance (in shares)	12,834
Granted (in shares)	766
Exercised or settled (in shares)	(391)
Forfeited (in shares)	(85)
Outstanding, ending balance (in shares)	13,124
Vested (in shares)	9,068
Outstanding Weighted-Average Exercise Price [Abstract]
Outstanding, beginning balance (in dollars per share)	$ 9.54
Granted (in dollars per share)	32.06
Exercised or settled (in dollars per share)	8.42
Forfeited (in dollars per share)	8.43
Outstanding, ending balance (in dollars per share)	10.89
Vested (in dollars per share)	$ 9.07
2013 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant and reserved for issuance (in shares)	20,900
2013 Stock Incentive Plan [Member] \| Equity Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0.0
2013 Stock Incentive Plan [Member] \| Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued liabilities	$ 15.0
2013 Stock Incentive Plan [Member] \| 5 Years Vesting [Member] \| Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 5 Years Vesting [Member] \| Time Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 4 Years Vesting [Member] \| Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 4 Years Vesting [Member] \| Time Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 3 Years Vesting [Member] \| Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2013 Stock Incentive Plan [Member] \| 3 Years Vesting [Member] \| Time Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2017 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant and reserved for issuance (in shares)	7,900		8,600
Risk-free interest rate	2.03%
Expected dividend rate	0.00%
2017 Omnibus Incentive Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of options	1 year
Assumed volatility	26.80%
2017 Omnibus Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of options	1 year 3 months
Assumed volatility	27.30%
2013 and 2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3.4
2013 and 2017 Plan [Member] \| Former Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3.8
2013 and 2017 Plan [Member] \| Equity Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1.4
2013 and 2017 Plan [Member] \| Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reduction in liability	$ 1.8